In light of the ongoing changes in our environment, some scientists are now suggesting that humans may be evolving into a new species that is better equipped to survive in a climate-altered world. This concept, known as “Anthropocene evolution,” suggests that as our planet continues to warm and experience other significant changes, our physical and behavioral characteristics may also be adapting in response. In this article, we explore the fascinating concept of Anthropocene evolution and how it could alter the course of human history going forward.
Evolution has been shaped by changes in the environment, including changes in climate. Looking at the origin and evolution of humans, we can see that many climatic changes have occurred over millions of years. Approximately six million years ago, human ancestors separated from a branch comprising chimpanzees and gorillas, which became known as hominin, including humans and our extinct human ancestors that could walk upright. This change corresponded to climatic changes.
All living beings have evolved from unicellular organisms, and if changes had not occurred, perhaps there would have only been microbes in the ocean. As life evolved, different branches of the tree of life kept changing until humans reached a particular branch. Bacteria that never changed perhaps lived in an environment that was constant, so they remained the same.
There are two kinds of changes in evolution: genetic and phenotypic (observable, physical changes). Genetic changes keep happening automatically, but they do not necessarily translate to changes in the human body or physical appearance. Physical changes occur only if there is a change in our diet or locomotion. For example, if a species ingests tough food, it will develop a heavy jaw. If it evolves to consume softer food, a heavy jaw is useless, so it recedes.
Simply put, if the climate does not change, humans or any living being will not evolve. When climatic conditions change, they induce changes in vegetation, and that has shaped human evolution. Climate change resulted in the most significant change in us: the brain size. That happened with our genus, Homo. The brain size of our ancestors belonging to the genus Australopithecus or Paranthropus or Ardipithicines was ape-like. They lived in climatic conditions that did not require a big brain. Approximately two million years ago, there were dramatic climatic changes. The conditions were not conducive for human survival. Hunter-gatherers had to move around, change their diet, communicate and develop strategies to hunt. This led humans to use their brains more, affecting the size of the organ.
The brain capacity almost doubled from Australopithecus. Within our genus, Homo habilis still had a lower brain capacity. But the brain capacity of Homo erectus and Homo heidelbergensis dramatically increased. We have seen this in our fossil record. In the present day, we see genetic changes due to climate changes. These changes allow people living in high-altitude regions or colder climates to live in extreme conditions. For example, Inuit have evolved to thrive in colder conditions for thousands of years. Tibetans also have a higher capacity to retain oxygen because they live at higher altitudes where oxygen levels are low. It takes time for genetic changes to translate into physical changes that can be seen.
Fossil records tell us that physical changes typically take 500,000 years to appear. Modern humans evolved somewhere around 300,000-500,000 years ago. Around this time, we became distinct from Homo heidelbergensis. And it took almost a million years for heidelbergensis to separate from Homo erectus. Physical changes occur gradually if climatic changes are also slow.
Drastic changes can also occur, but climatic fluctuations occur at a rate of hundreds of thousands of years. The human body is complex, and it takes millions of years for changes to occur. Every species evolves in its niche. If that niche becomes inhabitable due to climate change, the species would perish or migrate. Thanks to technology and modern medicine, humans have learned to survive. If something untoward were to happen due to climate fluctuations, there is every possibility that we would work around it, and humans may not go extinct.
Humans can survive and thrive in a variety of climates due to genetic changes and adaptations to new environments. New human species can arise in the current period if a population becomes isolated. For example, if Inuit become isolated from civilization and do not interact or interbreed, they may become physically distinct from the rest. Usually, changes begin with variation in a population, followed by races and sub-species, and finally, new species.
Denisovans, who lived until 30,000 years ago from Siberia to Southeast Asia, were adapted to high altitude and low-oxygen conditions. The population gave rise to people living in high-altitude regions such as Tibet. Europeans would see genetic changes if hot and dry conditions become recurrent. Europe was once warm and humid, and around 16-18 varieties of apes lived there. Then the climate changed, transforming Europe into a cooler place. All apes disappeared from the continent. Later, it became inhabited by Neanderthals who adapted to colder climates. Finally, Homo sapiens came in, capable of adapting to changing situations. Other human species died out because they could not adapt.
Climate change is expected to affect human evolution in the future. As the climate changes, humans and other living beings will need to adapt to survive. There is no doubt that our species is capable of adapting to new environments, but it is essential to take steps to mitigate climate change in the first place. By doing so, we can help ensure a more predictable and stable environment for future generations.
