In Brains, Size Is Not All that Matters
Two recent science articles indicate that scientists should be careful before inferring intelligence from brain size (picture). PhysOrg reported on work to uncover the genetic basis of microcephaly – reduced brain size in humans. “The cerebral cortex in particular has undergone a dramatic increase in surface area during the course of primate evolution,” the article claimed, yet acknowledged uncertainty about the causes and effects involved. “One particularly interesting feature of this new discovery is that the strongest links with cortical area were found in regulatory regions, rather than coding regions of the genes,” one researcher said. No causal links were drawn between more regulation and intelligence, nor brain size and intelligence. If the presence of mutations produces the disability of microcephaly, it does not follow that the absence of mutations will produce higher intelligence.
In the animal kingdom, consider the capabilities of a creature with one of the smallest brains on earth: the honeybee. The “amazing bee brain” was discussed in another article on PhysOrg. “Their brains are tiny – about the size of sesame seeds – and yet the behaviour of the humble honey bee is so advanced it has scientists scratching their heads in disbelief.” Packed into that tiny space is the ability to calculate distance and foraging efficiency independently, and communicate that information accurately to other members of the hive through an elaborate dance. This also presumes processing the input of visual, olfactory, auditory, taste and touch senses. Another article the next day on Science Daily discussed the complex maneuvers they perform on landing. A researcher is “optimistic that he will eventually be able to use his discoveries in the design of novel flight control systems.”
The first honeybee article discussed the “complex processing” that occurs in the bee brain. “Through their dance behaviour we get a window into bee psychology and perception,” said Dr Andrew Barron of Macquarie University. “Bees are beautiful little animals with great personalities – and we’re only just getting a sense of how smart they really are.”
Update Dec 24: an article on PhysOrg announced, “Ladder-walking locusts show big brains aren’t always best.” Here’s another insect with a tiny brain that can perform complex tasks, such as using visual cues for limb placement. “The study sheds new light on insects’ ability to perform complex tasks, such as visually-guided limb control, usually associated with mammals.” Dr. Jeremy Niven of Cambridge said, “This is another example of insects performing a behaviour we previously thought was restricted to relatively big-brained animals with sophisticated motor control such as humans, monkeys or octopuses.” Later, he said, “Big-brained mammals have more neurons in their visual systems than a locust has in its entire nervous system, so our results show that small brains can perform complex tasks. Insects show us how different animals have evolved totally different strategies for doing similar tasks.” If controlling four legs in a mammal is complex, imagine coordinating six legs in an insect, eight in a spider, or dozens in a millipede. The article ended by saying that “insects are often the inspiration for limb control in robotics.”
Human engineers pride themselves on packing more power into less space: music players, cell phones, computer chips and memory have shrunk dramatically in size since the 1960s. Why should the size of the human brain figure so prominently in human evolution stories? There has been a dark history of racist ranking by early Darwinists based on brain size. Even though that is taboo today, there is a kind of prehistorical racism that persists: Lucy, Ardi, Homo erectus, Neanderthals and other alleged human ancestors are often ranked in intelligence by skull capacity. How do they know that Homo erectus didn’t have a superior CPU packed into less space? There have been cases of humans doing just fine with small brains. Whales are not necessarily more intelligent for having brains much larger than ours. It’s not the size, the container or the materials; it’s the programming.
Amazing factoid: Packed into your cerebrum are more connections than all the electrical appliances on earth.
Stupid mythoid: It all just happened by evolution.