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Who you callin’ birdbrain? Why some birds with big brains can live almost as long as humans
Tardigrades might be the closest thing to immortal that we know of, but when it comes to creatures we actually can see, some birds can live as long as we do and even outlive us. Turns out it’s all in their head.
Birds with large brains are more likely to have long lifespans, as a team of scientists who studied bird brains has now found out. But how can an organ that is a total energy suck help an organism evolve to stick around on this planet longer? Powerhouse brains that are large in proportion to body size evolved to be flexible when it comes to responding to challenges, many of which include avoiding starvation and evading predators. That leaves room for figuring out other hacks for staying alive. Survival obviously adds years.
“I think our results confirm the benefits of enlarged brain size for some species, and could provide an overarching explanation for observed differences in brain size across vertebrates,” evolutionary biologist Alejandro Gonzalez-Voyer, who co-authored a study recently published in International Journal of Organic Evolution, told SYFY WIRE.
Because the brain burns so much energy—20% of calories that humans consume—it is obviously high-maintenance. The cognitive buffer hypothesis (CBH) could explain why it’s worth it. The brain is supposed to be a creature’s buffer against variation in the environment. CBH suggests that since this buffer is believed to increase as brains get bigger, the increase in size might have been an adaptation to surrounding changes. Coming up with new behaviors and improving old ones allowed brainy birds (and humans) to dodge many threats, and as such brains evolved, they left space for more adaptations that would extend how long something could stay alive.
"We were surprised to find an indirect effect of life history (or in other words investment into reproductive events), as it agrees with the direct association with longevity," Gonzalez-Voyer said. "Indeed, long-lived species tend to divide their lifetime reproductive investment into a larger number of events, investing proportionally less into each event, compared with short-lived species which invest more per event."
Birds even beat humans in one area. They have more neurons in their forebrains than most mammals, even primates. Think about that. Gonzalez-Voyer believes it could also contribute to living longer.
"it is possible that a greater density of neurons could provide greater cognitive abilities," he said.
The cognitive buffer effect hypothesis (CBH) maintains that the brain is supposed to be a creature’s buffer against variation in the environment, and that the increase in size might have been an adaptation to surrounding changes. Gonzalez-Voyer’s team saw something else after studying over 300 species of birds. They believe that in addition to CBH, slow life histories, including slow maturation, and long lifespans are actually a pre-adaptation for large brains to evolve. An Amazon parrot may get all its feathers at several months old, but doesn’t reach full maturity until the age of 15. Humans are comparable at 16, and our brains continue to develop until 25.
"An advantage we had in this study was really the analytical approach, which I co-developed," said Gonzalez-Voyer. "This approach allows us to disentangle direct from indirect associations among variables, and thus allowed us to separate (to a certain extent) the direct association between brain size and longevity from the association between body size and longevity. It also allowed us to make an indirect association between brain size and longevity through the effect on life history."
Larger parrots such as Amazons, African Greys, macaws and cockatoos are believed to have the intelligence of a human preschooler and can often live as long as humans. Alex the African Grey (RIP) was one of the most precocious parrots ever. He had a massive vocabulary, talked on command and his memory was so impressive, it would make you embarrassed to forget where you put your car keys. Parrots can be trained to follow commands and even talk in context. They may not understand the exact dictionary meaning of each word in a language, but they pick up on tone of voice and try to match phrases they already know with whatever human conversation they try to insert themselves into. Sometimes, they’re so dead on it’s scary.*
Ravens can also talk and pull off tricks like starting a car. Seriously, they are often on par with humans when solving problems. Poe was onto something when he said “Quoth the raven, ‘Nevermore’”. Gonzalez-Voyer doesn't think that being this smart is just a party trick.
“At least for birds, larger brain sizes could potentially provide advantages such as avoiding predation or surviving periods of food scarcity through the greater behavioural flexibility conferred by larger brains," he said. "By reducing the effect of extrinsic sources of mortality, then selection can act on intrinsic mortality, and thus greater longevity can evolve."
After this revelation, “birdbrain” should officially be considered a compliment.
*This information comes from your friendly neighborhood author’s years of experience with a Yellow-Naped Amazon that could possibly outlive her. Follow her @quothravenrayne on Instagram to see more of Lestat’s shenanigans.