About the episode
The researchers began working with a massive dataset of 1,500 mammals that contained information about brain and body size. Because whether it’s true or not, from an evolutionary perspective, the largest animals also have proportionally larger brains.
It has long been thought that this was linear, with brain size increasing proportionally as the animal got bigger. But the new model shows that it is curved. Very large animals have smaller brains.
Using this model, they were also able to identify animals that deviated from the rules. And humans are one of them. We evolved 20 times faster than all other mammals, resulting in this enormous brain.
There are many mammals that have undergone such an evolutionary leap. But not always with larger brains. Bats, for example, quickly evolved smaller brains at first.
The three groups of animals that have undergone the most dramatic changes in brain size are primates, rodents, and carnivores. In these groups, relative brain size tends to increase over time. But this is not true for all mammals.
In large animals, and some birds too, there is something that prevents the brain from growing too large. Perhaps it simply requires too much energy for a body of a given size.
Biologically, the animals in which this is seen are quite different, so it remains to be seen whether a reason can be found for all species to follow this curve.
Read more about the research here: Brain size mystery solved as humans leapfrog evolution
