Early human artwork from the Chauvet cave
Image from Wikimedia Commons
While learning about the process of evolution in class, I became interested in researching how species evolve over time, specifically the species Homo sapiens. Though the classic image of a monkey morphing into a Neanderthal morphing into a human is typically what one pictures, humans are not direct descendants of monkeys, nor are we modified versions of Neanderthals. We do, however, share a “recent” common ancestor with great apes (which includes chimpanzees and gorillas), a species that lived anywhere between 8 to 6 million years ago. Archaeological records show that the earliest humans lived in Africa, where they underwent most of their evolutionary changes. Around 4 million years ago, the hominid Australopithecus anamensis developed a major defining characteristic of humans –the ability to walk on two legs. Other human features that evolved later on include the formation of a relatively large and complex brain, the ability to utilize tools, and the capacity to communicate through spoken language.
In total, around 15 to 20 different species of early humans lived prior to the appearance of modern humans, who evolved in Africa around 200,000 years ago during a period of significant climate change. Like other species of humans, they were hunter-gatherers who developed certain behaviors to help them adapt to the harsh conditions. More advanced traits, such as the ability to create simple art and the development of cultural practices, evolved much later. Soon after, around 80,000 to 60,000 years ago, modern humans migrated to Asia; during this time period, our species was nearly wiped out by extreme climate change, which reduced the population to only about 10,000 adults of reproductive age. The other species of humans that remained –Homo erectus, Homo neanderthalensis, and Homo floresiensis –would eventually become extinct. Finally, around 12,000 years ago, the first signs of human-regulated agriculture appeared, marking a significant turning point in our history and paving the way towards complex civilization.
Reading about the origin of our species was extremely interesting, and gave me some perspective on the time it took for us to develop all the complex characteristics we have today. It is also interesting to note that our “sister” species, the Neanderthals and Homo floresiensis, disappeared only about 17,000 years ago –a relatively short amount of time when compared to the length of their existence. Knowing how long it took for humans to evolve, are there any significant evolutionary changes that have occurred in humans within the past 2,000 years? In this article in Time Magazine, studies have shown that there clear signs that humans are still evolving. Unlike the process of evolution in our predecessors, who toiled outside all day and were more exposed to environmental dangers, “natural selection” today is more likely to favor traits that provide modern-day benefits. These traits include mutations that allow for digestion of milk and resistance to certain diseases like malaria, and changes that affect brain development.
Since the Industrial Revolution, modern humans have also grown taller and healthier, but are surprisingly much weaker physically than our prehistoric counterparts. According to the article, a prehistoric Aborigine could have easily beaten Usain Bolt in a race, and a typical Neanderthal woman had more muscular strength than most bodybuilders today. These evolutionary differences can be largely explained by changes in lifestyle and cultural practices. Reproductive patterns, for example, are responsible for the likelihood of mutation among offspring. Among older men, sperm is more likely to carry mutations; since men used to have more children at an older age, they were more likely to transmit mutations to their offspring. Now, they tend to have children at a younger age, thus reducing the potential for genetic variation and slowing down the process of evolution.
So, despite the relatively short amount of time since the existence of modern civilization, human beings have already undergone a few changes, both genetically and physically. Considering how much we’ve evolved since our early days, perhaps there is still hope that we will develop superpowers in the future. Though if that were to happen, it would probably be in the form of a new human species that would eventually replace us as the reigning humans on Earth…Luckily, it’s doubtful that we’ll ever evolve that much.