Human beings are the peak of evolution, right? Our advanced brains allow us to poke one another on Facebook, send rockets to the moon, and order complex drinks at Starbucks. We can even fall in love. How are we able to do all of that? NPR’s Science Podcast has been doing a running series “The Human Edge” in which they discuss various things about humans that make us, well, human. NPR’s John Hamilton tackled brain evolution and how we humans still carry parts of other ancestral animal brains within us. Feel that pebble in your shoe? Thank a jellyfish. Ever duck before a rogue Frisbee collides with your noggin? Thank a lizard. Remember where you left your keys? Thank a mouse.
Hamilton interviewed David Linden from John Hopkins University who explained that our brain is the way it is because evolution is “the ultimate tinkerer and cheapskate.” Evolution built our brain by taking simpler brains and just piling more brains on top – like adding scoops of ice cream to an ice cream cone. Hence, the pieces of our brain inherited from these other creatures are largely unchanged. The result is that our advanced, intricate, special gray-matter is spectacularly inefficient, poorly designed, and ill-suited to many of our daily needs. On the flipside, evolution’s Frankensteinian cobbling together of various animal brains is precisely why human beings can experience higher emotions like love. Our ice-cream-cone-brain has created some of our best, and most uniquely human, attributes. After the jump is an illustrated guide of how the forces of natural selection shaped your mighty mind from distant relatives of jellyfish, lizards, and mice.
The Cone: Nervous Jellyfish
Jellyfish were among the first animals to evolve anything resembling a nervous system, specifically a “nerve net.” Our sensory nervous system, the part that lets you know if your hand is on a hot stove, sends signals the same slow way as the jellyfish nerve net does and at the same slow speed: 100 meters per second. For perspective, Hamilton notes that a landline telephone signal is “a million times faster.” The speed of thought is none-too-impressive in the age of electronics.
An example: if your foot was a mile away and someone shot you in that same foot, you would see the gun shot instantly, hear it four seconds later, then feel it twelve seconds after hearing it – a full sixteen seconds after the gun was actually fired. Nerves are sloooooow.
Pro: Without the jellyfish neural net, our nervous system would never have evolved. You couldn’t shake a hand, feel sun on your skin, or pull away from a cactus.
Con: Your nerve cells would communicate more quickly if they yelled messages to one another.
First Scoop: Instinctive Lizard
“Lizard brain” has become somewhat synonymous with our base instincts. Fight-or-flight reactions originate here, as do many of your unconscious reflexes, like ducking when you see something hurdling towards your head or automatically trying to catch something you drop. The downside is that fears of public speaking and panic attacks are related to your lizard brain misinterpreting a stressful situation as dangerous and overriding the rational, relaxed part of your mind. The “lizard brain” represents many core, instinctual actions.
Pro: The lizard brain is as close to a Spider-Sense as a normal person is going to get. You react to danger unconsciously.
Con: Because the lizard brain reacts to danger unconsciously, you don’t get to pick when it decides to hijack your higher functions, send you into fight-or-flight and kick on the adrenal glands. Not convenient when giving a presentation at work.
Second Scoop: Memory Mouse
The mammalian brain at is exemplified by that little workhorse of science labs everywhere: the mouse. Mice brains are able to remember and anticipate. Memory is what lets a mouse solve a maze it’s seen before and the expectation of cheese is what encourages a mouse to figure out a new one. In short: a mouse brain can process time. It can remember the past and guess at the future in a rudimentary way. Every time you remember how to walk hom