1/6/2024 0 Comments Who has the biggest brain app![]() In contrast to the dominant view and our own expectation, we found that social challenges contributed by decreasing brain size. But surprisingly, it was ecological challenges that expanded brains. We found that a combination of ecological and social challenges do produce the brain size we see in humans. Living in difficult environments such as the African savanna may have have prompted humans to evolve big brains. So we don’t know what’s cause and what’s effect. It cannot tell whether large brains evolved to solve the difficult problems or whether they evolved for other reasons and then enabled their bearers to crack the hard problems. While many studies have found such associations, there is a problem with this approach. Or do they live in large groups where they face lots of social problems? For example, do primates or other animals with large brains have a diet that is challenging to find but nutritionally rewarding? This would indicate an ecological origin. The common approach is for scientists to look at many species and investigate whether large brains are associated with specific problems. It’s been done before, but we did it in an unusual way. We set out to test the ecological and social hypotheses. Such challenges may have forced humans to learn how to track prey, build tools and light fires out of dry sticks. These include having to find food in a seasonally changing savanna, having to store food to be eaten later and having to prepare or cook food so it’s easy to eat. In contrast, other hypotheses propose that ecological problems were key. Essentially, these problems are moving targets, thought to produce arms races in brain sizes leading to exaggerated brains, and possibly to human brain sizes. Solving a social problem requires you to anticipate how friends and foes are going to react to your every move. The reason social problems have long been the favourite explanation is because they seem particularly difficult to solve – ranging from cooperating with friends to hunt big animals or raid other groups to skillfully cheating foes or avoiding being cheated. However, they differ when it comes to pinpointing what these problems were. Hypotheses for the evolution of the human brain size all agree that brain expansion increased our ability to solve problems. ![]() But our new study, published today in Nature, finds evidence against this idea and shows that human brain expansion was likely driven by ecology. This is puzzling, as the brain is very costly – burning 20% of the body’s energy while accounting for only 4% of its mass.Īs evolution tends to remove waste, how come we evolved such large, energy-consuming brains? There are many different ideas out there, with the dominant hypothesis suggesting that challenging social interactions were the driving force. But the human brain is almost six times bigger than expected for our bodies. Most animals have brains in proportion to their body size – species with larger bodies often have larger brains.
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