Many people believe that humanity has conquered nature thanks to the wonders of civilization and technology. Some people also believe that because humans are so different from other creatures, humans have complete control over their destiny and no longer need to evolve. But this is not true – humans today continue to evolve. Portal theconversation.com speakWhy.
Humans have two hands that help us use tools carefully. We can walk and run on two legs, which frees our hands to perform this delicate job. And our big brains allow us to think logically, come up with new ideas, and live well with others in social groups.
All these characteristics have helped humans develop culture. It includes all of our ideas, beliefs, planning and thinking abilities. Culture also includes a person's ability to change his or her own environment – for example, by using tools or growing food.
Although humans have dramatically changed the world around us in a variety of ways over the past few thousand years, evolution in turn has also changed humanity. We never stop evolving—it's just that today's evolutionary development takes different forms than it did in our ancient ancestors.
For example, take the relationship between humans and sunlight. The sun is vital to life on Earth, but ultraviolet radiation can damage human skin. People with pale skin are at risk of sunburn or even skin cancer. And people with more pigment in their skin will be better protected from ultraviolet rays. Therefore, dark-skinned people in the tropics are better able to survive than pale-skinned people in bright sunlight. But ancient people didn't need dark skin – they moved to cloudier, cooler regions… This stopped the production of vitamin D, which is necessary for normal bone development in children and adults.
Next is food. 10,000 years ago, the ancestors of modern humans began domesticating animals such as cattle to eat meat. After another 2,000 years, they learned how to milk cows and goats. Unfortunately, like most other mammals of the time, adult humans could not digest milk without getting sick. More precisely, almost all adults – except those with the necessary genes.
Milk was such an important food source for early humans that people who were able to digest milk were able to survive better than others and have more children. So their genes spread until humans acquired this ability almost everywhere.
This process that took place thousands of years ago is an example of what science calls cultural and biological co-evolution. That is, the cultural practice of milking animals has led to genetic and biological changes.
Others, such as the Inuit of Greenland, have genes that allow them to metabolize fat without developing heart disease. The Turkana people of Kenya are herders in very dry regions of Africa and they have a gene that allows their bodies to survive for long periods of time without water. Others will experience kidney damage because they regulate fluids in the body.
Finally, humans, like all other living things, are susceptible to a variety of infectious diseases. In the 14th century, a plague pandemic killed one-third of Europe's population. Many survivors have a special gene that helps them resist the disease. And the descendants of these people were better able to survive the epidemics that raged in the following centuries.
