Not all Environments are Created Friendly

We learned that we grow and develop according to a precise plan that was set in advance in our first cell. At the same time, our growth and development do not depend on that plan alone. The environment within which our growth occurs is also quite important. Here is how, and why.

It is unlikely that human populations ever lacked oxygen in their entire history. This is because, even after the long evolution of our species, when we are deprived of oxygen we can only survive for a few minutes. If our ancestors had been exposed to conditions where oxygen was occasionally and temporarily unavailable, as was the case with water and food, then only those who can last longer than others without oxygen would survive. As a result, natural selection would make us more resistant to oxygen deprivation. Interestingly, there are some human populations where this was indeed the case. Tribes of Bajau divers from Southeast Asia are also known as “sea nomads”. Their villages are built on wooden pillars protruding from the sea. Bajau divers can endure for minutes diving below the surface. In fact, they spend up to two-thirds of their time each day looking for food under the sea. They simply do not have other sources of food in their habitats. As a result, their spleens increased by about 50% compared to average humans, which is an adaptation known and described in seals, too. This is somewhat surprising, given that people can survive without the spleen when it needs to be surgically removed. This probably suggests that we still do not understand all the roles…