Climate change is the architect of new human species

Climate change is the architect of new human species

Subject :Environment

Section: Climate Change

Context: Fossil records tell us that physical changes typically take 500,000 years to appear

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• Changes in water availability, rainfall, temperature and humidity, either globally or locally, can shape evolution. Looking at the origin and evolution of humans, many climatic changes have occurred over millions of years. Six million years ago, human ancestors separated from a branch comprising of chimpanzees and gorillas.
• This new branch became known as hominin, which includes humans and the extinct humans and our immediate ancestors that could walk upright. This change corresponded to climatic changes.
• Humans have evolved from unicellular organisms, thanks to climatic conditions. If conditions had not changed, perhaps there would have only been microbes in the ocean. If you look at life as a tree, the branches kept changing until humans reached a particular branch.
• The bacteria that did not change perhaps lived in an environment that was constant, so they stayed the same.
• There are two kinds of changes: genetic and phenotypic (observable, physical changes). Even now, 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, and it recedes.
• Climate change resulted in the most dramatic change in us: the brain size. That happened with our genus, Homo. The brain size of our ancestors belonging to the genus Australopithecusor Paranthropus or Ardipithicines were ape-like. They lived in climatic conditions that did not require a big brain. Their diet and lifestyle did not need that either.
• Approximately two million years ago, there were dramatic climatic changes. The conditions were not conducive to human survival. Hunter-gatherers had to move around, change their diet, communicate and develop strategies to hunt. They needed to build tools to survive. So humans began to use their brains more, which would have affected the size of the organ.
• The brain capacity almost doubled from Australopithecus. Within our genus, Homo habilis still had 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.
• 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.
• Seeing genetic changes in Europeans if hot and dry conditions become recurrent. Around 13-14 million years ago, Europe was warm and humid. Roughly 16-18 varieties of apes lived there. And 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. Much later, Homo sapiens came in. They were smart enough to adapt to changing situations. They migrated to greener pastures. Other human species died out because they could not adapt. Every species evolves in its niche.
• And if that niche becomes inhabitable due to climate change, the species would perish or migrate.