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Does technological developments terminate the evolution of human species?

Does technological developments terminate the evolution of human species?


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One of the most agreed upon mechanism for evolution is natural selection.Changing environmental conditions necessities development of variations that enable the survival of that particular species.These genetically passed down variation later becomes the adaptive features which further result in development of new species.

But with development of technology we are finding newer ways to cope up with changes in the environment.Do this impact human evolution?


"Natural selection" is a somewhat misleading term. Evolution does not need "natural" selection to occur; it only needs selection. Even the term "selection" is a bit misleading because it's often thought of as referring to the death of individuals or, somewhat more accurately, as reduced likelihood of producing offspring, due to lower fitness.

In fact, any process that gives individuals with particular genetically determined features - a reproductive advantage in a given ecological niche will drive evolution among the sub-population within that niche.

Addressing your question more directly: Suppose technology leads to people whose keyboarding talents are high having more children. If so, it will tend to drive evolution among the sub-population having access to keyboards toward genotypes having higher keyboarding talents. But if having keyboarding talents results in those individuals having less likelihood of producing children, evolution in that sub-population will be driven in the opposite direction.

IF it could be said that technology in general decouples human reproduction from "natural" influences like disease, resource availability, climate, etc., it could then be said that evolution will be less driven by those influences and more driven by, e.g., the cultural tendencies of particular sub-populations to produce more children. But that would be a gross over-simplification.

It is almost certain that changes in technology have had significant influence on human evolution. Agriculture, clothing, tool use, etc., have all had long-term consequences in human evolution.

Human culture is very complex, and separating out all the effects of technology on differential reproduction rates among sub-populations would be extremely difficult; but it's almost certain that there are such effects.


Evolution is not a path towards perfection/improvement but simply a series of changes over time. Thus, as McGrew explained, technology can have an effect on what drives our evolution but cannot stop evolution: nothing can actually, because changes happen even by simple chance (see e.g. genetic drift).


Evolution: Changing Species Over Time

Evolution is the process by which species adapt over time in response to their changing environment. Use these ideas to teach about the water cycle in your classroom.

Photograph by James L. Amos

Evolution is an important field of study for scientists. It covers the study of changes organisms have undergone over time in response to different factors in their environment. All organisms, including humans, evolve over time. Evolution occurs through natural selection, and is a force that has shaped every organism living today.

Darwin’s Finches

Have the students read about and research the finches Darwin studied on the Galapagos Islands. Darwin noticed that different finches had differently shaped beaks. He also noticed that the various beak shapes were each best suited for handling certain types of food. Darwin knew that the finches had come from continental South America originally, but those that he saw on the islands were unlike the ones on the mainland. Darwin wondered what caused these finches to change when they made it to the Galapagos Islands. Have students test the ability of different beaks to get different types of food. Provide students with spoons, forks, metal binders clip, and tweezers to represent different types of beaks and food bowl with foam packing peanuts, small bird seed, large bird seed (sunflower seeds), and toothpicks. Have student try the different tools and identify which tool works best with which foods.

National Geographic Explorer Jingchun Li: Evolution of “Living Solar Panels”

The first thing you notice when visiting a healthy marine coral reef is the number of different fishes and the many bright colors of both the fishes and the corals. Marine biodiversity refers to the richness of different species living together in a community. Have the students read about National Geographic Explorer Jingchun Li and her research on marine biodiversity and biologically productive coral reef ecosystems. Li is studying how coral reefs and other organisms are undergoing macroevolution to cope with the stresses created by human disturbances to their ecosystem.

Divide students into groups. Ask the students what stresses are taking place in the marine environment that coral reefs and other marine organisms need to adapt to. Have them divide into small groups and research these changes and design solutions to address these disturbances.

Human Evolution

Scientists who study early humans depend on fossil evidence to help them sort out how our ancestors evolved over time. When looking at the fossils, scientists look for clues to changes in different characteristics such as brain size, skull shape, locomotion, and jaw size. Have the students read about the history of human ancestors. Then have work through the Mystery Skull Interactive to use clues to identify fossils.

Evolution in Isolation

Have the students watch the video on Papua&rsquos Winged Beauties, about the birds living on the island of Papua in Indonesia. This isolated island is a paradise with a lush and resource-rich habitat. Male birds of many different species have evolved elaborate ways of attracting mates. Ask the students, why is it important for a species to have the strongest males mate with the females and how does this affect the species?

National Geographic Explorer Jeremy Emiland Martin: Evolution of Crocodiles

Have the students read about Jeremy Emiland Martin&rsquos work on the evolution of crocodiles and then have them research how modern crocodiles have been evolving since the time of the dinosaurs. Because crocodiles are found in so many different areas of the world, it is important to go back to where they first emerged to learn about their evolutionary beginnings. Ask the students, how have crocodiles evolved since the Cretaceous Period? What might have caused crocodiles to evolve? Why were these traits favorable in this particular environment?

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Related Resources

Evolution

In the mid-1800s, Charles Darwin famously described variation in the anatomy of finches from the Galapagos Islands. Alfred Russel Wallace noted the similarities and differences between nearby species and those separated by natural boundaries in the Amazon and Indonesia. Independently they came to the same conclusion: over generations, natural selection of inherited traits could give rise to new species. Use the resources below to teach the theory of evolution in your classroom.

Theory of Evolution

The theory of evolution is a shortened form of the term &ldquotheory of evolution by natural selection,&rdquo which was proposed by Charles Darwin and Alfred Russel Wallace in the nineteenth century.

Human Evolution

Learn how early humans evolved from Homo habilis, to Homo erectus, to Homo sapiens and developed basic survival tools.

The Evolution of Big Cats

Learn how today's big cats evolved from prehistoric cat-like organisms, and what factors contributed to their evolution.

Related Resources

Evolution

In the mid-1800s, Charles Darwin famously described variation in the anatomy of finches from the Galapagos Islands. Alfred Russel Wallace noted the similarities and differences between nearby species and those separated by natural boundaries in the Amazon and Indonesia. Independently they came to the same conclusion: over generations, natural selection of inherited traits could give rise to new species. Use the resources below to teach the theory of evolution in your classroom.

Theory of Evolution

The theory of evolution is a shortened form of the term &ldquotheory of evolution by natural selection,&rdquo which was proposed by Charles Darwin and Alfred Russel Wallace in the nineteenth century.

Human Evolution

Learn how early humans evolved from Homo habilis, to Homo erectus, to Homo sapiens and developed basic survival tools.

The Evolution of Big Cats

Learn how today's big cats evolved from prehistoric cat-like organisms, and what factors contributed to their evolution.


Milestones in Human Evolution

Early humans had evolved upright posture and the ability to walk upright on short legs. Male canine teeth were about equal in size to females’, which indicates a significant shift in social life.

Broad knee joints indicate clear adaptation to regular bipedal walking.

Oldest definite early human footprint trails, with footprints of other animals and environmental evidence.

Early humans made basic tools and ate meat obtained from large animals.

Clear evidence of a double-curved spine, which indicates a shock-absorbing system associated with bipedal walking.

Robust hip bone and lengthened thigh bone indicate that human ancestors could walk farther, faster and more easily.

Early humans dispersed from Africa to Asia.

First major technological innovation. Hand axes are made. Hand-axe technology persists for more than 1.2 million years.

Early humans had control of fire and created hearths.

Beginning of the most rapid increase in early human brain size (relative to body size). The fastest pace of brain enlargement took place between 800,000 and 200,000 years ago.

Evidence of brain enlargement implies considerably prolonged maturation of the young. Early humans hunted large animals.

Early humans made shelters. Early humans invented wooden thrusting spears.

Early humans began to communicate with symbols—with evidence of the oldest known “crayons” (faceted sticks and chunks of pigment).

Modern humans (Homo sapiens) evolved in Africa they gathered and hunted food, like earlier human species. The date of 200,000 years is based on the oldest known H. sapiens crania and the estimated age of convergence (back in time) of all the mitochondrial DNA diversity recorded in living human populations. Three species of early humans overlapped in time with H. sapiens. The other three species became extinct between about 70,000 and 17,000 years ago.

Modern humans collected and cooked shellfish.

Modern humans had evolved prolonged periods of childhood growth, as found in people today.

Between 135,000-100,000 years ago:

Modern humans temporarily spread beyond Africa. Modern humans made shell beads, the oldest known jewelry.

Modern humans exchanged resources over long distances.

Modern humans became capable of capturing fast and dangerous prey.

Earliest recorded purposeful burial.

Between 100,000-32,000 years ago:

Neanderthals (H. neanderthalensis) created rare carved plaques and pendants.

Modern humans made special tools for fishing.

Modern humans recorded information on objects. Modern humans became capable of making clothing by perforating hide.

Near-extinction of H. sapiens. Greatly reduced population, with numbers estimated at about 10,000 adults of reproductive age to as few as 600. Timing correlates with repeated, large-scale droughts in portions of Africa.

Homo erectus became extinct.

Modern humans began a series of permanent worldwide migrations.

Modern humans created permanent drawings.

Modern humans reached Australia.

Modern humans reached Europe.

Modern humans created paintings and figurines.

Modern humans created musical instruments.

Modern humans became capable of making well-fitted clothing using bone needles.

Neanderthals (H. neanderthalensis) became extinct.

Modern humans made baskets.

H. floresiensis became extinct, leaving modern humans (H. sapiens) as the sole survivors of the once diverse human evolutionary tree.

Modern humans reached the Americas (by at least this date).

Beginning 12,000 years ago:

Humans become a “turning point” in the history of life as they control the growth and breeding of certain plants and animals. Farming and herding ensue, which transformed natural landscapes—first locally, then globally. Food production led to settlement (villages, towns, cities) and population growth.

First domestication of plants and animals.

Modern humans use symbols to represent words and concepts.

Human population doubled from 3 billion to 6 billion people in just 40 years.

At least 83 percent of Earth’s land surface had been directly affected by humans.


Human Evolution: History, Timeline, and Future Predictions

The human evolutionary tree is a complex structure, branching and re-branching at several points along the timeline. Though a complete study of human evolution is beyond the scope of one article, it endeavors to highlight the main stages, and also tries to makes predictions about the next step in the ongoing process of human evolution.

The human evolutionary tree is a complex structure, branching and re-branching at several points along the timeline. Though a complete study of human evolution is beyond the scope of one article, it endeavors to highlight the main stages, and also tries to makes predictions about the next step in the ongoing process of human evolution.

Did you know?

All males amongst modern-day human beings possess a Y chromosome inherited from a male that lived in Africa about 140,000 years ago.

Would you like to write for us? Well, we're looking for good writers who want to spread the word. Get in touch with us and we'll talk.

The story of human evolution isn’t just a single tale. It is actually a collection of several short stories, each connected to the other like the links in a chain. The human tribe, or the hominini, has evolved over millions of years, from creatures you would scarcely imagine to have anything in common with. We are the result of the adaptive evolution of several different species. Thus, in essence, within each of us, you can find the ghosts and spirits of many ancient animals of the past.

But we humans are basically primates, and therefore, our history must have more to do with that of the monkeys or the chimpanzees, than say, for example, a fish. We have the same five fingers, the same front-facing eyes, and even have similar behavior and habits as them. But believe it or not, humans, monkeys, chimpanzees, and indeed all the animals that we see around us today were all fish once living in the oceans. Therefore, in order to learn about our past, we have to learn about not just the monkey, but also the fish inside us.

So let’s take a journey through the sands of time and let the tale unfold. This is the fascinating story of our bodies, and why we are built the way we are. This is the story of human evolution.

The Story of the Fish That Walked 400 MYA – 350 MYA

If I were to tell you that your earliest ancestor was a fish, would you believe me? Of course you won’t! A monkey maybe but a fish, no way! However, in all probability, that theory is true, and the evidence for it is present right there in your hands.

It is a widely accepted fact that life on earth began in the oceans. Nearly 3.6 billion years ago, the first living things in the form of simple celled organisms first appeared in water. These simple cells later combined to form multi-cellular life forms almost 1 billion years ago, and soon the oceans were swimming with all kinds of living things, including various fish, aquatic plants, etc.

Then, close to 365 million years ago, some ancient fish used their fins to crawl out of the oceans onto the lands. In order to move there, their fins evolved into feet and claws of reptiles, which later evolved into the paws of mammals with short fingers all pointing the same way. As these mammals spread over the lands and began living in various habitats, they evolved further, and finally their claws became hands, as these primitive mammals evolved into the first primates we are all the descendants of.

The Tale of Notharctus Tenebrosus 54 MYA – 38 MYA

Notharctus lived 54 to 38 million years ago. Though from its first fossil discovered in 1870, it was thought to be a member of an obsolete order of the mammalian family, the later discovery of an almost complete skeleton firmly established it as being a primate. It lived high up in the canopy of large ancient trees.

Notharctus is linked with humans, because it shared with us a unique characteristic – the opposable thumb. Life in the trees caused the lengthening of its fingers and the addition of an opposable thumb in order to allow it to reach the edible flowers and fruits growing at the ends of thin branches.

Would you like to write for us? Well, we're looking for good writers who want to spread the word. Get in touch with us and we'll talk.

Northarctus Tenebrosus had large hind limbs, and a tail which helped it to balance itself on the branches of trees. It must have had a body weight of around 10 lb, and from head to tail would have been nearly 40 cm long.

Notharctus and the following species which lived amongst the foliage provided us with another important characteristic – our color vision. Early primates saw only a limited range of colors, but then one group developed full red green and blue (RGB) vision, to distinguish the ripe fruits from the green unripe ones. Thus, we not only owe our ability to grasp (opposable thumbs) but also our full color vision to the lives led by Notharctus and our early ancestors high up on the trees.

The Tale of the Elusive Ancient Primate 8 MYA

According to studies, modern-day humans share 98% of their DNA composition with chimpanzees. This fact indicates that our race and that of the chimpanzees must have had a common point of origin. In fact, many theories suggest that the human tribe, or the hominini, and all the other species and subspecies within our genus, including the modern-day apes such as gorillas and chimpanzees must have all descended from the same ancient primate.

However, fossil-based evidence hasn’t been able to substantiate this theory, and perhaps it never will, because of the complexity involved in the classification and establishment of the relationship between the fossils of the numerous ape-like creatures of the time.

This elusive ancient primate, our common ancestor, must have evolved from the Notharctus species, and is believed to have existed 8 million years ago.

The Tale of Ardipithecus Ramidus – The Bipedal 5.6 MYA – 4.4 MYA

For several years, anthropologists had believed that bipedalism (the human ability to walk on two legs) was developed in response to changes in the habitat of our ancestors from woodlands to grasslands. However, the discovery of a new species – the Ardipithecus Ramidus in 1994, turned that theory right over its head.

Ardipithecus Ramidus lived mainly on trees, as is evidenced from its bone structure. However, the discovery of its skeleton showed that it had a hip bone structure which is remarkably similar to ours. Studies have concluded that such a hip structure must have enabled it to walk upright, though the reasons for it to do so are still unknown. One theory suggests that it must have stood up to have a larger field of vision while on ground where it must have felt less safer than up on the trees.

The Ardipithecus lived in the African continent, was 4 ft tall, and a good climber. It used all four limbs while on trees, but stood upright to walk on the ground. The members of this species also had smaller canines, which is another indicative factor towards our common lineages. However, another species was found that lived about the same time as Ardipithecus Ramidus, and which too was bipedal,. This discovery has since had many anthropologists debating about our relationship to it, with some even questioning whether Ardipithecus was even a hominini at all!

The Tale of ‘Lucy’ in the Ground with Earthworms 3.2 MYA – 1.7 MYA

In 1974, the fossilized remains of a female primate was found in Ethiopia. She was named Lucy, after the Beatles’ song Lucy in the Sky with Diamonds. Dating methods indicated that Lucy lived 3.2 million years ago. Another excavation in 1978 showed distinct tracks of human-like footprints made by members of the same species, walking on two legs (bipedal). This species was named Australopithecus aferensis, after the people and the land of Africa.

Thus, it is now believed that the single line of evolution from fish to reptiles to mammals and finally to primates must have branched off into two different lineages, nearly 6 million years ago. One ultimately leading to the gorillas and the chimpanzees of present day, while the other to modern-day human beings.

Many believe that the first in the human line of evolution was, not the Ardipithecus, but the Australopithecines, which lived in the continent of Africa nearly 3 million years ago. Just like the Ardipithecus, the members of this species displayed several distinct characteristics linking them to modern-day human beings, the most significant of which was the development of bipedalism, or the ability to walk on two legs.

The Australopithecines show skeletal features distinct from other primates and closer to that of modern human beings. They had a greater forearm-to-upper arm ratio as compared to other hominids of the time, and exhibited increased sexual dimorphism. Fossils reveal that the average height of adults was up to 1.5 meters (4.9 ft), and their weight was nearly 120 lb. Skull fossils indicate that their brains had a volume of about 600 cc.

Australopithecines later subdivided into various subspecies, including Australopithecus anamensis, A. sediba, A. africanus, and A. afarensis, with each showing subtle differences compared to the other. All these sub-subspecies thrived in various parts of the continent of Africa, till they finally became extinct almost 2 million years ago.

The Complex Story of the Homo 2.58 MYA – Present

Whether it was the Ardipithecus Ramidus or the Australopithecines, it is still unknown. But one thing is for sure, it was one of those two species that evolved into the final link in our chain of evolution – the genus Homo.

The long and complex homo lineage first began around 2.4 million years ago. Tracing the entire line along with all its branches down to us and establishing a relationship between each link is an almost impossible task. There are many species and subspecies within the genus homo which could or could not be related to us. The scientific opinion too, in this matter, is divided into many different camps, leaving us with the single option of detailing only the most significant members of this genus.

Among the earliest members of the homo genus were the homo habilis. These primates were very resemblant to the Australopiths in a number of ways. For instance, they too had long hanging arms. However, unlike the Australopiths, they had smaller teeth and much more human-like arms and feet. Their faces too were less protruding. They were short in stature, and had a brain size of 510 cc, which is roughly less than half the size of ours. Many homo habilis findings are accompanied with stone weapons, which points towards the development of mental capacity and intelligence. They lived in Africa nearly 2.33 million years ago.

Homo ergaster, or the African homo erectus, succeeded H. habilis. Their physical constitution evolved to be more nearer to modern human beings, but their brains, though larger than the H. habilis, were still smaller than ours. They are estimated to have been over 6 ft in height, with a less protrusive forehead, and smaller jaws and teeth. They had longer noses with downward-facing nostrils. They also had significantly larger brains compared to H. habilis, with skull findings pointing towards a cranial capacity of nearly 900 cc.

The H. erectus species thrived and existed for almost 1.5 million years. During this large span of time, they migrated out of the African continent and spread to other continents, including Europe and Asia, as is evidenced by their fossils found there. Homo erectus were also the first primates to use fire and hunt with weapons.

Lastly, in the final stages of human evolution, the neanderthals and the homo sapiens came into existence about 200,000 years ago. Both these species developed complex brain structures, and gave birth to language and culture, and their later members began to wear clothes.

Homo neanderthalensis, or the neanderthals, were very similar to modern-day human beings, with their DNA differing from ours by just 0.12%. They had larger brains than ours (1,600 cc), but at the same time had a larger bodily structure as well. The last of the neanderthals died out in Europe close to 40,000 years ago.

Early homo sapiens had nearly the same brain size as that of ours (1,350 cc), but had characteristic thick skulls and a prominent forehead. The rest of their anatomy was nearly similar to that of ours. Homo sapiens is the last surviving species of the genus homo, and modern-day human beings, or the homo sapiens sapiens are its subspecies.

The Untold Story of the Man From the Future In the Future

Human kind has come a long way. We were fish once, and now we eat fish for dinner! Our evolution has been phenomenal. So what does the future have in store for us? What evolutionary changes will modern-day human beings undergo? What will they look like in the future?

These certainly are interesting question, albeit, not very easy to answer. Making random predictions about the future can be dangerous. The great fictional detective Mr. Sherlock Holmes says, “I never guess. It is a shocking habit, destructive to the logical faculty”. However, when on a difficult case, often, he too would dare to predict, provided that there were enough facts to support his assumptions. The future of human evolution is one such challenging mystery. So, following the lead of Mr. Sherlock Holmes, in the following few lines, we too shall dare to predict the future evolution of present-day human beings, based on as many facts as we can gather.

Loss of Muscle Mass: Present-day humans hardly get any exercise. The majority of us live very sedentary lives. Thus, it is quite possible that future humans will have significantly less muscle mass, and will rely on machines to do all the physical work.

Increased Myopia (Nearsightedness): Our ancestors lived in the wild. They required a large range of vision to scour the landscape. But, with most of us migrating to the cities, and with our cities getting more and more congested, we are hardly ever required to see more than 20 ft. away. This problem is more likely to escalate in the future. Thus, it is safe to assume that in the future, our myopia will increase and our hyperopia (farsightedness) will decrease.

Increased Skull Size: The muscle that works the most is the muscle that grows. This fact foretells that, considering that modern-day humans use their brains a lot more than older generations, it is quite possible that future humans will have increased skull size to accommodate their gigantic brains.

Lower Immunity: Advanced medicines of the future will enable us to fight off diseases much more efficiently than our natural immune system. Therefore, in the future, we will no longer need to have an immune system to protect us.

Racial Uniformity: Our ancestors originated in Africa, and later moved to various other continents, including Asia, Europe, Australia, and America. The different environmental and climatic conditions of these different regions caused them to undergo further physical changes, and this gave rise to different races and ethnicity. But thanks to the advances in the modes of transportation and communication, the world is becoming one again. With modern human society becoming a mixture of people of different ethnicity intermingling and living together, it is quite in the books that in the future, the lines of distinction between various races shall blur, and future human beings will most likely go back to being one uniform race again.

Lesser Teeth and Smaller Toes: Fossils of feet show that our ancestors had wider feet with longer and spread toes. But since hardly any of us goes about barefoot anymore, it is likely that in the future, our feet will be smaller with shorter toes. Also, since we ingest only cooked food, which is softer and hardly requires any chewing, possibly in the future, humans will have very small teeth.

Taller and Balder: Humans today are better fed and protected against the elements of nature. Thus, our descendants are most likely to grow taller as well as have lesser hair on their bodies.

Increased Life Expectancy: “And when he shall be immortal, he shall become a God.” ―Anonymous. Though immortality might still be a distant dream, humans of the future will definitely live longer and better lives, just like we do when compared to our ancestors.

Selective Evolution-playing God: With all the terrific advances in science, especially in the field of genetic engineering, parents in the future will literally be able to ‘manufacture’ their children based on their personal preferences.

So, there you have it, a collection of short stories, which when combined together, form the single great tale of human evolution. We have come a long way, and the journey until now has been more than just exciting. From a single cell floating in the ocean waters, we have managed to become the multi-cellular wonders of nature that we are today. Where we will go from here, predictions apart, only time can tell.

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The past, present and future of human evolution

María Martinón-Torres is a palaeoanthropologist, director of the National Research Centre on Human Evolution (CENIEH) in Burgos, Spain, and an honorary reader at University College London.

You can also search for this author in PubMed Google Scholar

A 1.8-million-year-old skull discovered in Dmanisi, Georgia, is one of the oldest hominin fossils found outside Africa. Credit: Valerie Kuypers/Epa/REX/Shutterstock

Close Encounters with Humankind: A Paleoanthropologist Investigates Our Evolving Species Sang-Hee Lee W. W. Norton: 2018.

Many people assume that palaeoanthropology deals only with the past. The thinking goes that, beyond a curious, somehow romantic interest in the early accounts of our ancestors, there is not much that this discipline can add to the understanding of present-day humans. South Korean palaeoanthropologist Sang-Hee Lee disputes that view in Close Encounters with Humankind. She shows us to ourselves as the living (and, importantly, still changing) outcome of a wonderful interplay between biology and natural selection over the roughly 6 million years since hominins diverged from the chimpanzee lineage.

Avoiding the usual narrative, from bipedal ape-like creature to complex behaviour, Lee offers an original journey along our singular evolutionary path. When did our ancestors lose their fur? Did the taste for meat change our destiny? Was farming a blessing or a curse? Is altruism unique to us? Succinctly and engagingly, Lee revisits these and other key questions about the story of our evolving species — and gives some unconventional answers.

Notably, she supports multiregionalism. This is the theory that modern humans originated in many places simultaneously, in contrast to the ‘out of Africa’ model that posits a single origin for our species. Thus, she counters the sometimes rigid interpretations of the fossil record propounded in a literature dominated by the English language and the Western scientific community. In her book, Asia makes a comeback as a birthplace of modern humans and their ancestors. Lee reminds us that the Dmanisi hominin fossils from the republic of Georgia are as old as the earliest Homo fossils found in Africa and that Homo erectus might have originated in Asia and migrated “back into Africa” to give rise to later Homo species. She also discusses the Denisovans, the mysterious hominins that coexisted with modern humans and left behind extensive DNA, but few fossils. She refers to them as “Asian Neanderthals” to highlight how the reconstruction of European hominins’ evolutionary story should not be disconnected from that of their Asian cousins.

The site near Beijing where the 750,000-year-old ‘Peking Man’ Homo erectus fossils were found. Credit: Granger/REX/Shutterstock

Not everything in Close Encounters with Humankind is about the past. Are humans still evolving? It’s commonly thought that our interaction with the world through culture and technology (such as clothes, tools or medicines) has buffered the pressure on our bodies to adapt biologically to the environment. Lee challenges this view and traces a cascade of other evidence for ongoing human evolution. She points to studies on skin colour as evidence.

Dark skin is thought to have evolved in the first furless hominins in Africa, to protect against the ultraviolet radiation in intense direct sunlight. Hominins living in higher latitudes, went this line of reasoning, would be exposed to less UV radiation, and so would need less-active melanocytes (the cells that produce the pigment melanin). That might largely explain the lighter skin of populations in regions farther from the Equator. However, studies by geneticist Iain Mathieson, now at the University of Pennsylvania in Philadelphia, and his colleagues on a large ancient-DNA sample from western Eurasian populations revealed that the light skin of Europeans is due to a new gene variant that emerged no more than 4,000 years ago (I. Mathieson et al. Nature 528, 499–503 2015). They link these populations’ lighter skin to the rise of agriculture and sedentary communal lifestyles, a view Lee favours.

As she shows, the shift to agriculture led to a diet based on processed grains and starches, which is deficient in many nutrients, including vitamin D. This deficiency forces the body itself to synthesize the vitamin — a metabolic process requiring the absorption of UV through the skin. The mutation for paler skin in Europeans pinpointed by Mathieson would maximize the UV absorption in populations facing low vitamin D intake. With this example, Lee emphasizes how culture — in this case, agriculture and a change in diet — might even have accelerated evolution.

Farming also led to a population explosion, despite increased vulnerability to infectious disease in settled communities. The availability of cereals allowed earlier weaning of infants, and meant women could give birth at shorter intervals. The resulting population increase brought higher genetic diversity, “the raw material of evolution”. Another demonstration of how our biology is still subject to change is the lactase mutation that has allowed some humans over at least the past 5,000 years to digest milk into adulthood. This eccentricity, less common in East Asia (predominantly China), became a key advantage for pastoralists and might represent an additional mechanism for overcoming the scarcity of vitamin D, because cow’s milk is rich in the nutrient.

Moreover, living in communities is central to our species’ success. As Lee notes, large groups became essential to survival because they offer assistance, to offset the difficulties of giving birth to big-brained babies and caring for them through a long infancy. Modern humans are also the longest-living primate species: three generations can overlap in time. Individuals stay ‘useful’ beyond their reproductive period by taking care of their children’s offspring and even unrelated infants. As Lee states, the concept of “fictive kin” (close bonds with those outside family or marriage) is unique to humans. She notes the remains of an elderly hominin in Dmanisi, dated to 1.8 million years ago, that evidently survived for some time without teeth, at a time without sophisticated tools or the knowledge of how to control fire. That could indicate that the hominin was treated with compassion by the group: the fossil could be the earliest evidence of human altruistic behaviour.

Lee’s style is breezy. A chapter entitled ‘King Kong’ discusses Gigantopithecus, the puzzling gigantic ape found in China that might have coexisted with Homo erectus from 1.2 million to 300,000 years ago. ‘Breaking Back’ looks at back pain as a trade-off of bipedalism. That accessibility sometimes risks over-simplifying, and occasionally strays into territory where every trait seems to have a function or to have evolved for a use.

Yet, ultimately, Lee will inspire even experts with her efforts at elucidating a field often seen as arid and inscrutable. Close Encounters with Humankind emphasizes how much the past matters. Our 6-million‑year story has been massively shaped by chance and a changing environment. Lee shows that, now more than ever, our decisions can shape the future of Earth and its inhabitants, including ourselves.


Transcendence Happens All the Time

The ongoing coronavirus pandemic might not seem like an obvious cue for thinking about biological transcendence. But the strange thing is that in our response to this crisis we&rsquove been unwitting participants in just such an event.

The idea of transcendence goes back a long way, under a variety of names and guises. In many religions it captures the notion of deities or phenomena that exist somehow independently of the physical universe and even beyond physical laws. Philosophers like Immanuel Kant modified aspects of this concept and created a label for things that are literally unknowable and that exist outside of knowledge itself.

But in recent times transcendence has become associated with the notion of humans going beyond our default form of consciousness often conflated with the mystical idea of &ldquoascendance&rdquo to some higher form of existence&mdasha trope eagerly adopted by scores of not-really-trying-very-hard science fiction stories, movies and futurists. Most of the slightly more-grounded versions of these speculations see humans and machines melding into something new. Maybe our consciousnesses and memories&mdashour &ldquoself&rdquo&mdashcould be uploaded to immortal digital form, swirling around the internet or in some omnipotent supercomputer.

These fantasies are quite alluring (and they really are fantasies at this point we don&rsquot understand consciousness or the full physical basis of memory and behavior, so the odds of mapping &ldquoyou&rdquo into a machine seem pretty slim). They&rsquore also a great distraction from the surprising and very real examples of such transformations that are happening right now, under our noses.

Take the novel coronavirus SARS-Cov-2. Its genetic material is a single strand of RNA with 29,903 nucleotides (the &ldquoletters&rdquo of the genetic code common to all known life on Earth) that contain information for about 30 genes for making proteins. (A virus is &ldquosimply a piece of bad news wrapped up in protein,&rdquo in words that have been attributed to biologists Peter and Jean Medawar.)

Whatever the precise origin of this specific type of coronavirus, the informational content of that strand of RNA had, until early 2020, never existed in the world in any other form than the polymerized nucleotides of biochemistry. Every single copy of SARS-Cov-2 was a bundle of molecules and nothing more. But then, almost overnight, it jumped to an entirely new substrate.

Starting from the innards of PCR sequencing systems and technology like nanopore devices (that literally pull a strand of DNA or RNA through a molecular sensor that registers different electrical charges for different nucleotides) the viral RNA was converted into digital data symbolic representations that are themselves encoded as tiny electrical or magnetic bits in silicon memory or hard drives. From here the informational content of the viral RNA was duplicated: across storage devices, through the internet, into cloud servers, onto people&rsquos laptops, cell phones, flash drives and to some extent into their brains as trained researchers pored over the gene sequences and their associated molecular machinery.

This viral transcendence hasn&rsquot just stopped at the replication of symbolic information though. That same information now interacts with the world in ways that it couldn&rsquot when locked up in viral RNA. Now it influences human activity and behavior. We run computer codes, we write scientific articles, we build pieces of the RNA artificially in labs, and in the case of our mRNA vaccines we generate trillions, even quadrillions, of duplicates of small pieces of the original RNA, the sonnets of spike protein coding, and ship them across the world where they go into human flesh and cells and ribosomal machinery.

The informational content of this one type of virus has spread across the Earth in all of these forms, electronic and artificial, to a degree that may even compare to the terrifying efficiency of the original biological forms themselves. It has also now exerted its influence on the environment containing it in ways that the original form could never have. Electrical energy has flowed in every sequencing study and every file download or protein structural prediction. Lab equipment and vaccine production facilities have been fabricated or expanded, and humans have scurried this way and the other as the genomic information has been wrangled and studied.

In a very real sense, the coronavirus uploaded itself to machine form and then beyond. Even if we were to eradicate its biological form from the world it would live on as a digital species, perhaps largely dormant, but from the perspective of self-propagating information, time is somewhat irrelevant. If the digitized version of the virus is uninspected for a century or two it doesn&rsquot matter, it still continues to exist because it can, winning the game of Darwinian evolution.

Just like our own &ldquoselfish genes,&rdquo the viral genes built from nucleotides are really only a convenient implementation, or instantiation, of a type of information that describes its own processes of propagation (albeit in compressed form). But it took the evolutionary development of a species like ours, and our subsequent technological evolution, to create the opportunity for viral transcendence into wholly nonbiological form. There may be a lesson in that: we might like to think that we can implement some version of our own transcendence once day, but perhaps it will be something else that creates the opportunity and more or less does it whether we want it to happen or not. We may not upload ourselves to machine forms the machines may upload us, just like we do for viruses.

The way that information propagates in the world is examined in much more detail in my new book The Ascent of Information (Riverhead, June 2021).

This is an opinion and analysis article.

ABOUT THE AUTHOR(S)

Caleb A. Scharf is director of astrobiology at Columbia University. He is author and co-author of more than 100 scientific research articles in astronomy and astrophysics. His work has been featured in publications such as New Scientist, Scientific American, Science News, Cosmos Magazine, Physics Today and National Geographic. For many years he wrote the Life, Unbounded blog for Scientific American.


For the vast majority of the history of our kind we were in some ways no more sophisticated than crows, which use sticks to poke around in promising holes. Eventually, of course, we discovered fire and invented stone tools, which then led to guns, pesticides and antibiotics. Using these tools, we encouraged the survival of favorable species such as wheat and yeast needed for beer and cows for meat and milk&mdasha garden of delights.

But we also encouraged a garden of neglect&mdasha surprising number of resilient pests that have been able to survive in spite of our weapons. These species are now coming back to haunt us as toxins, pathogens or worse. Here are ten ways we have helped this garden of neglect prosper.

1. SHARP ROCKS, SOFT FLESH. In the beginning someone held aloft a sharpened rock. "Progress!," he screamed out, or maybe, "Ouch!," depending on which end he grabbed. With that first stone weapon and its many pointy descendants, life changed. Our initial impact would have been small. However, by 10,000 years ago we had extinguished many of the largest species on Earth&mdashmastodons, mammoths, American cheetahs, giant kangaroos and many more. In our wake, we left behind smaller species more able to reproduce rapidly or escape detection in the first place.

As humans came to rely on tools to survive, those with hands better able to make and wield those tools were more likely to pass their genes to the next generation. Mary Marzke at Arizona Sate University in Tempe argues that hand bones of humans are quite different from those of other primates because of our use of tools. Our hands are better able to manage the subtle grips necessary for making and using tools to maim or kill other species. In response to our first tools the animals around us changed. So did we.

2. BIG FISH, LITTLE FISH. Not only have we altered the course of big game evolution on land but we've also effectively reduced the size of fishes in the sea. Fishermen prefer to catch big fishes, and fishing regulations tend to prohibit the harvest of the smallest individuals of a species. In response, fishes have evolved the ability to reproduce at a smaller size and/or younger age. If they can breed before they get big enough to be harvested their genes stand a much higher chance of being passed on. American plaice, Atlantic cod, Atlantic herring, Atlantic salmon, brook trout, and chinook salmon all have appeared to grow more slowly and/or to reproduce at smaller sizes where and when they are heavily fished (Jorgenson et al., 2007 Palcovacs, 2011) Once, a large cod could eat a small boy. Now, a small boy could almost eat an entire cod.

3. RESISTANCE IS FUTILE. Bacteria have been evolving in response to threats from other species, including fungi, for hundreds of millions of years. Bacteria and fungi compete for food and often do so using chemical warfare. A fungus evolves an antibiotic and bacteria evolve resistance, so fungi evolve a new antibiotic. Recently, though, things changed. We invented (or rather stole from fungi) antibiotics, which allowed us to kill bacteria&mdashand, importantly, treat bacterial infections. However, by using them too much, too incompletely or too indiscriminately we cause bacterial strains resistant to our drugs to evolve. Unlike fungi, we cannot retaliate by simply evolving new antibiotics. Hundreds of bacterial lineages have evolved resistance to more than a dozen of our antibiotics. In response, we are forced to discover new antibiotics, an endeavor that has proved ever more difficult.

4. GOING (ANTI)VIRAL. Viruses generally evolve even more quickly than bacteria. For example, multiple drugs for HIV infection are taken together as a cocktail for one reason: the HIV virus evolves quickly. The cocktail slows the evolution of full resistance. Even if HIV evolves resistance to one drug, the odds it will evolve complete resistance to all three are far lower. Similarly, the flu that usually starts each year in Asia is different by the time it reaches North America. The flu virus evolves to get by not only as a function of how we respond to it but also in response to our population size and patterns of movement. It, and other viruses, even evolve within our bodies. The virus that makes you sick is almost inevitably different than the one you give someone else.

5. PESTICIDES. In wild grasslands up to one third of the living mass of plants is eaten by herbivores. In our crop fields just 10 percent is eaten. The difference is in part the result of the more than 2.3 billion kilograms of pesticides we use annually to control pests. Though in holding back the pests, we also kill many beneficial species and favor varieties resistant to our pesticides. Resistance to pesticides has evolved in hundreds of species of insects. In addition to pesticides for insects, farmers also use fungicides to kill fungi. Nearly all fungicides have led to the evolution of new resistant strains of plant pathogens (Gould).

6. HERBICIDES. Any patch of land, left alone, will tend to sprout with plants bent on outcompeting each other, rising higher and higher into the sky to win access to the sun. Once, we prevented such competition by weeding our fields and sorting crop seeds from weed seeds, one by one. This selection depended on visual acuity and caused multiple lineages of weeds to evolve seeds resembling those of our crops. Now we exclude weeds using herbicides, whether in our lawns or our fields, before they bear their seeds. The weeds evolve resistance to herbicides, becoming invisible to our chemicals rather than our eyes. More than a hundred species of weeds have evolved resistance to one or another herbicide. We clear the ground, till the soil and spray the fertilizer and herbicide, and when we do, row by row the resistant weeds grow.

7. ENVIRONMENTAL TOXINS. The environmental toxins we produce are everywhere. Often they influence the health and well-being of species around us sometimes they also influence their evolution. PCBs (aka polychlorinated biphenyls) were once used in industrial coolants. Whereas PCBs are good coolants, they are toxic. PCBs kill fish and other animals, in part by blocking one of the receptors in their bodies, AHR2. The fish with ordinary receptors simply died where PCBs were plentiful, leaving behind food and habitat. Those fish with slightly different receptors, to which the PCBs bound less well, survived and eventually thrived. PCBs were never meant to be used to control other species. Nevertheless, they had the effect of killing some (but not all) of the species and individuals they came into contact with, strongly favoring the individuals with resistance of one form or another. Nor are PCBs unique. Many of our pollutants&mdashbe they heavy metals, cadmium, oil and others&mdashappear to lead to rapid evolution of tolerant and, at least sometimes, toxic creatures.

8. OF MICE (AND RATS) AND MEN. Mice and rats have been following humans since at least the origins of agriculture more than 10,000 years ago. It is easy to imagine we have probably been trying to kill them for nearly as long. More recently, however, we've been poisoning these pests, offering them tempting treats laced with deadly chemicals. Rats living in forests and other wild places are attracted to new foods in particular and so feed readily from such baits. Rats living with humans are not, at least not anymore. Present them with a new food and they will wait. Several authors have suggested that this "neophobia" in urban rats has evolved in response to the threat posed to rats and mice by our new "foods." For now, the little we know about the evolution of neophobia fits with this idea. The clearest evolutionary change in rats and mice as a result of our interference has been the evolution of resistance to the rat poison warfarin. We then created superwarfarin to target these resistant populations, but resistance to this poison has recently evolved (Mayumi et al., 2008). Once again our garden of neglect is seemingly growing out of our control.

9. URBAN JUNGLE. Plant species living in urban environments tend to be surrounded by patches of habitat less suitable than the ones in which they are situated. Seeds that disperse far from their mothers are more likely to end up in those less suitable surroundings (think: concrete or pavement Cheptou et al., 2008). As a consequence some city plants have evolved to produce fewer, larger seeds that fall near them rather than smaller ones that can disperse farther away. Although this type of quick evolution lends a short-term survival advantage, it may mean that these plants are less robust to adapt to a changing environment in the future. Meanwhile, thousands of other city species are acquiring new survival mechanisms despite the ways we build our cities, whether that means evolving the ability to eat concrete, call more loudly to their mates or simply find a place among our towers of glass and steel to hide.

10. THE NEW GALÁPAGOS. Our stone weapons and antibiotics are just a few of the tools we've created that have inadvertently helped shape the evolution of the species around us. Simply moving around has caused changes, too, many of which may be innocuous but all of which are unintentional. We have moved cane toads, wild pigs, mice, rats, weeds, sparrows, pavement ants and thousands of other species around the world with us. These species have responded to our tools, but they have also responded to the climate and organisms already present in the places we have introduced them. A recent study in Australia found most of the hundreds of plant species introduced there show some evidence of recent evolution, post-introduction, with many of them apparently having evolved smaller, more drought-tolerant forms (Bushwell et al., 2011). Cane toads introduced to Australia are evolving longer legs that aid in colonizing new habitats (for example, Philips et al., 2007). Where cane toads are present snakes are evolving smaller mouths (those with bigger mouths eat cane toads and, in doing so, die). Vultures introduced to the Canary Islands have evolved larger bodies (Agudo et al., 2010). Elsewhere, house sparrows (Johnston and Selander, 2008), cane toads, houseflies and many other species show evidence of evolving differently in different places. Each new place to which we introduce organisms is a kind of island and the species, new versions of Darwin's Galápagos birds.

Ultimately, whereas evolution can be whimsical (think: vampire bats), its general tendencies are predictable. It revisits its best-worn routes. If we continue to manage the world around us as we have managed it in the past, it's likely we'll continue to favor even more of those species that thrive despite us, species that are resistant to our drugs, pesticides and toxins. Such species might get bigger or more beautiful, but probably not. And, a world filled with small, resistant species is not necessarily what we want. It's time to use our knowledge of evolution and its well-worn paths to cultivate a new garden as we plan our future, one seeded with species that benefit rather than harm us.

References:
General articles&mdashFor a great, albeit slightly older, review of the evolution of resistance in general, see Fred Gould's article&hellip Gould, F. 1991. "The evolutionary potential of crop pests." American Scientist 79. Gould, F. 1991 (http://www4.ncsu.edu/

Sharp rocks, soft flesh&mdashFor a review of this interesting literature, read Marzke's recent review, but also any of the good papers that build on it in recent years. Marzke M. W., Marzke R. F. 2000. "Evolution of the human hand: approaches to acquiring, analyzing and interpreting the anatomical evidence." J Anat 197: 121&ndash140.

Big fish, little fish, more little fish&mdashSee a nice recent review by Erik Palkovacs. Palkovacs, E. P. 2011. "The overfishing debate: an eco-evolutionary perspective. Trends in Ecology & Evolution 26:616-617. doi: 10.1016/j.tree.2011.08.004

Going (anti)viral&mdashAn interesting recent study, for example, examines the rates and details of evolution of the hepatitis C virus within individual hosts compared with those as it moves among hosts. This study found the virus to actually evolve more quickly within a particular host, be that you or someone you know, than among hosts. Gray, R. R., et al. The mode and tempo of hepatitis C virus evolution within and among hosts. BMC Evolutionary Biology 201111: 131. http://www.biomedcentral.com/1471-2148/11/131/

The new Galapagos&mdashTo my mind, among the most exciting of these recent studies are those on cane toads, who, in arriving in new places appear to be both evolving and shaping the evolution of other species. See the work of B. L. Phillips, including the recent paper, Phillips B. L., Brown G. P., Shine R. 2010. "Evolutionarily accelerated invasions: the rate of dispersal evolves upwards during the range advance of cane toads." Journal of Evolutionary Biology 23, 2595&ndash2601.doi:10.1111/j.1420-9101.2010.02118.x

ABOUT THE AUTHOR(S)

Rob Dunn is a biologist at North Carolina State University and a writer whose articles have appeared in Natural History, Smithsonian and National Geographic, among other publications.


Human Embryology

One branch of embryology is human embryology. Scientists in the field have added to our knowledge of the human body by discovering, for example, that there are three major embryologic categories of cells, called the germ cell layers, in our bodies. The layers are:

  • Ectoderm: Forms the epithelium, the thin tissue that creates the outer layer of a body's surface and lines the alimentary canal and other hollow structures, which not only covers the body but also gives rise to cells in the nervous system.
  • Endoderm: Forms the gastrointestinal tract and associated structures involved in digestion.
  • Mesoderm: Forms the connective and "soft" tissues such as bone, muscle, and fat.

After birth, some cells in the body continue to proliferate, while others don't and remain or are lost in the aging process. Aging results from the inability of cells to maintain or replace themselves.


The savannah hypothesis states that hominins were forced out of the trees they lived in and onto the expanding savannah as they did so, they began walking upright on two feet. This idea was expanded in the aridity hypothesis, which posited that the savannah was expanding due to increasingly arid conditions resulting in hominin adaptation. Thus, during periods of intense aridification, hominins also were pushed to evolve and adapt.

The turnover pulse hypothesis states that extinctions due to environmental conditions hurt specialist species more than generalist ones. While generalist species spread out when environmental conditions change, specialist species become more specialized and have a greater rate of evolution. The Red Queen hypothesis states that species must constantly evolve in order to compete with co-evolving animals around them. The social brain hypothesis states that improving cognitive capabilities would allow hominins to influence local groups and control resources. The Toba catastrophe theory states that there was a near-extinction event for early humans about 70,000 years ago.


Inbreeding shaped the course of human evolution

TALK about an inauspicious beginning. For thousands of years our ancestors lived in small, isolated populations, leaving them severely inbred, according to a new genetic analysis. The inbreeding may have caused a host of health problems, and it is likely that small populations were a barrier to the development of complex technologies.

In recent years, geneticists have read the genomes of long-dead humans and extinct relatives like Neanderthals. David Reich of Harvard Medical School in Boston has now sequenced the Neanderthal genome and that of another extinct human, the Denisovan, to an unprecedented degree of accuracy. He presented his findings at a Royal Society meeting on ancient DNA in London on 18 November.

Describing the genomes as “nearly error-free”, Reich says both species were severely inbred due to small populations. “Archaic populations had low genetic diversity, really extraordinarily low,” he said. “It’s among the lowest diversity of any organism in the animal kingdom.”

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One Neanderthal, whose DNA Reich obtained from a toe bone, had almost no diversity in about one-eighth of the genome&colon both copies of each gene were identical. That suggests the individual’s parents were half-siblings.

That’s in line with previous evidence of small populations, says Chris Stringer of the Natural History Museum in London. “In the distant past, human populations were probably only in the thousands or at best tens of thousands, and lived locally, exchanging mates only with their nearest neighbours.”

Our genomes still carry traces of these small populations. A 2010 study concluded that our ancestors 1.2 million years ago had a population of just 18,500 individuals, spread over a vast area (PNAS, doi.org/dv75x8).

Fossils suggest the inbreeding took its toll, says Erik Trinkaus of Washington University in St Louis, Missouri. Those he has studied have a range of deformities, many of which are rare in modern humans. He thinks such deformities were once much more common (PLoS ONE, doi.org/p6r).

Despite the impact on health, it is unclear whether inbreeding could have killed off the Neanderthals and Denisovans. More likely is the effect of small populations on culture and technology, says Mark Thomas of University College London. Larger populations retain more knowledge and find ways to improve technologies. This “cumulative culture” is unique to humans, but it could only emerge in reasonably large populations. In small populations, knowledge is easily lost, which explains why skills like bone-working show up and then vanish, says Trinkaus.

Tiny populations may have prevented Neanderthals and Denisovans from developing cumulative culture. “It would place some limits on their cultural complexity,” says Thomas. The same thing held our species back, until the population reached a critical density, unleashing the power of culture – at which point there was no stopping us.

“Tiny populations may have prevented Neanderthals from developing more advanced technologies”

The genomes also show that early human species interbred with other hominins (see “We’re all Homo, aren’t we?“). Many of us carry genes from Neanderthals, or from the mysterious Denisovans, who are known only from a single cave in Siberia.

We’re all Homo, aren’t we?

Early hominins weren’t picky about their sexual partners. We already knew that our species, Homo sapiens, interbred with two other hominin species, the Neanderthals and Denisovans.

Now it looks like the Denisovans did some interbreeding of their own. Some stretches of the Denisovan genome look much older than the rest, says David Reich of Harvard Medical School. The most likely explanation, he says, is that the Denisovans interbred with an unidentified species and picked up some of their DNA. The question is, who?

It could be evidence of a new species of hominin, as yet unknown to science. Alternatively, it could be the first genetic record of one of the many known species. Johannes Krause of the University of Tübingen in Germany suspects it was the latter, since many hominin species identified from their fossils have never been genetically analysed.

The most likely candidate is Homo heidelbergensis, says Chris Stringer of London’s Natural History Museum. This species lived between 600,000 and 250,000 years ago, and spread from Africa into Europe and western Asia. That means Denisovans, whose ancestors followed a similar path, could well have met them.

This article appeared in print under the headline “Inbreeding shaped human evolution”