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Home , Convergent evolution

INTELLEGENCE OVER TIME: THE OF INTELLIGENCE IN CORVIDS AND APES BY KATIE SANKO

itty, a New Caledonian crow, became great intelligence. In fact, advanced cogni- Currently, there are several hypotheses for Kfamous when National Geographic tion has evolved in many taxa.9 While the the factors behind this convergent evolu- highlighted her ability to solve a puz- intelligence of such as chimpan- tion. Tese factors mainly fall under the zle that bewildered many fve-year-old zees has been widely publicized, it has broad categories of dietary and social. children.5 In order to obtain a small piece also been found that in the group of Apes rely on a diet of tropical , and of meat foating in a tube of water, Kitty corvids (crows, jays, ravens, ect.) have cog- one hypothesis behind their advanced placed rocks in a seemingly unrelated tube, nitive abilities comparable to apes.4 Exam- cognition is centered on this diet. Many causing the water to rise and the meat ples of higher cognition in both primates only bear ripe fruit at certain times to foat to the top.5 Kitty and her fellow and corvids include object permanence of the year, and these plants were widely crows possess remarkable cognitive ability, (memory for objects that cannot be seen dispersed throughout the habitats of early prompting many to wonder what could be by the organism),4 the delay of gratifcation primates11. Because these primates were behind the evolution of such intelligence. (control of impulsivity),4 and mental time ofen required to travel large distances to Animal intelligence is tricky to defne, travel (memory for past events and plan- forage for food, larger brains and more despite the eforts of numerous researchers ning for future events)4 and tool making.1,13 complex cognition allowed for the pri- over the years. A quantitative measure of Although the brains of these organisms are mates to travel the most energy-efcient animal intelligence has yet to be agreed structuredof these organisms are struc- routesw. upon. It is ofen assumed that as brain size tured diferently,4 their intellectual abilities Corvids, however, do not rely on (both absolute and relative) increases, so are remarkably similar,4 thus making the ripe fruit. Instead, many corvids “cache” does intelligence. However, both of these evolution of intelligence in these groups food, and cognitive evolution would have measures have been ruled out by bascre- particularly fascinating. aided their common ancestor in remem- search. For example, cetaceans ( and Te evolution of intelligence in crows and bering the location of its caches3. Further- ) have a larger absolute brain size apes can be described as convergent evolu- more, corvids such as the Western scrub than ,10 yet humans are considered tion. Convergent evolution is the devel- jay know when the food in their cache is far more intelligent. Similarly, the shrew’s opment of similar traits in organisms that going to spoil and become inedible3. Simi- brain contains 10% of its body mass while are not closely related. Although larly, many corvids steal from the caches of a ’s contains only 2%. Generally, and birds share a common ancestor with other birds and employ complex strategies the defnition of intelligence involves the all , approximately 300 million to prevent their ownyear, and these plants performance of complex behaviors and the years separate them from their closest were widely dispersed throughout the use of novel solutions to problems.10 relative, indicating that their advanced habitats of early primates.11 Because these Humans are not alone in the possession of cognition must have evolved separately.4 primates were ofen required to travel large

FALL 2016 | Berkeley Scientifc Journal 47 distances to forage for food, larger brains ous relationships with others in their spe- behind the intelligence of these groups and more complex cognition allowed for cies. For example, male chimpanzees will also revolve around cooperation within the primates to travel the most energy-ef- compete for “alpha” status and therefore these . Social learning has great cient routes.11 mating rights, requiring the formation of evolutionary benefts as individuals that Corvids, however, do not rely on ripe fruit. complex relationships with many individ- can learn from others expend less energy Instead, many corvids “cache” food, and uals. Meanwhile, females ofen collaborate and time learning by themselves13. Both cognitive evolution would have aided their to protect their young from violent males. corvids and apes have shown to learn from common ancestor in remembering the lo- amongst one another. As apes are polyg- watching others, indicating that social- cation of its caches.3 Furthermore, corvids amous, males are ofen in competition cooperation within these species. Social such as the Western scrub jay know when for mating rights.13 Many primates keep learning has great evolutionary benefts the food in their cache is going to spoil and up numerous relationships with others in as individuals that can learn from others become inedible.3 Similarly, many corvids their species. For example, male chim- expend less energy and time learning by steal from the caches of other birds and panzees will compete for “alpha” status themselves.13 Both corvids and apes have employ complex strategies to prevent their and therefore mating rights, requiring the shown to learn from watching others, own caches from being stolen.7 Certain formation of complex relationships with indicating that social species, including the scrub jay, will not many individuals.13 Meanwhile, females is important to their survival.13 cache food if they detect another jay near- ofen collaborate to protect their young Such social complexity, along with the ca- by.7 Tey have also been known to move from violent males.13 pacity for social learning, requires a large caches if they believe a competitor may Contrastingly, many corvids are mo- amount of cognitive ability, thus encour- have witnessed them hiding food.7 nogamous and do not experience as aging the selection for intelligence. Along with dietary quandaries, apes’ much competition for mates as apes do.13 Interestingly, the brain structures of birds common ancestor commonly faced many Terefore, it was unlikely that competition and mammals difer. brains social challenges that promoted the evolu- for mates encouraged cognitive evolution contain a structure known as the neocor- tion of intelligence.13 Firstly, primates that in corvids.13 In this way, the diferences in tex, which was considered to be the part live in groups are ofen subject to amongst mating represent an example of a hypoth- for many mammals’ advanced cognition.4 one another. As apes are polygamous, esis that applies to one of the taxonomic Since birds did not possess a neocortex, it males are ofen in competition for mating groups but not the other.13 was thought that intelligence in birds was rights13. Many primates keep up numer- Along with competition, hypotheses impossible4. However, as experimental

Along with competition, hypotheses behind the intelligence of these groups also revolve around cooperation.within these species.

48 Berkeley Scientifc Journal | FALL 2016 evidence indicating that corvid birds are Evolution of Brains and Cognitive Ability, capable of cognitive feats comparable to Evolutionary , 73-87. Retrieved apes increased, researchers realized that from link.springer.com. the neocortex is not a requirement for 9) Morand-Ferron, Julie, Cole, Ella F. and advanced intelligence.4 Quinn, John L. (2016) Studying the evo- In conclusion, the convergent evolution lutionary ecology of cognition in the wild: of intelligence in corvid birds and apes re- a review of practical and conceptual chal- veals that this area of study is complex and lenges. Biological Reviews, 91, 367–389. requires more research. Te surprisingsim- 10) Reader, Simon M., Et al., (2005). Com- ilarities between apes and corvids indicate paring cognition across species. Trends in that convergent evolution of intelligence Cognitive Science, 9. 411. may be worth looking into in taxa that 11) Potts, R. (2004). Paleoenvironmental have been previously dismissed in terms of basis of cognitive evolution in great apes. intelligence. Furthermore, more research American Journal of Primatology, 62(3), should be done on the brains of corvid 209-228. doi:10.1002/ajp.20016 birds in order to determine the physical 12) Roth, Gerhard and Dicke, Ursula. source of their complex behavior. Tese (2005). and Intel- results could be applicable to other species. ligence. Trends in Cognitive Sciences, 9, All in all, the evolution of intelligence is a 250-257. fascinating subject that is far more com- 13) Seed, A., Emery, N. and Clayton, N. plex than we understand. (2009), Intelligence in Corvids and Apes: A Case of Convergent Evolution?. Etholo- REFERENCES gy, 115: 401–420. 1) Alex A. S. Weir, Jackie Chappell and 14) Taylor, Alex H., Gavin R. Hunt, Jenni- Alex Kacelnik (2002), Shaping of Hooks in fer C. Holzhaider, Russell D. Gray. (2007). New Caledonian Crows. Science, 297, 981. Spontaneous Metatool Use by New Cale- 2) Emery, Nathan J. (2006) Cognitive orni- donian Crows, Current Biology, 17(17), thology: the evolution of avian intelligence. 1504-1507 Philosophical Transactions of the Royal 7 Society B, 361, 23-43. 3) Emery, Nathan J. and Clayton, Nicola S. IMAGES (2004). Te Mentality of Crows: Conver- 1)http://www.bbc.com/news/science-envi- gent Evolution of Intelligence in Corvids ronment-35159872 and Apes. Science, 306, 1903-1907. 2) http://www.centerforgreatapes.org/ 4) Güntürkün, O., & Bugnyar, T. (2016). treatment-apes/about-apes/ Cognition without Cortex. Trends in Cognitive Sciences, 20(4), 291-303. doi:10.1016/j.tics.2016.02.001 5) Langin, K. (2014, July 24). Are Crows Smarter Tan Children? Retrieved November 15, 2016, from http://voices. nationalgeographic.com/2014/07/24/ animals-crows-smarts-intelligence-sci- ence-minds/ 6) Lefebvre, L., Reader, S. M., & Sol, D. (2004). Brains, Innovations and Evolu- tion in Birds and Primates. Brain, Be- havior and Evolution, 63(4), 233-246. doi:10.1159/000076784 .com. 6) Lefebvre, L., Reader, S. M., & Sol, D. (2004). Brains, Innovations and Evolution in Birds and Primates. Brain, Behavior and Evolution, 63(4), 233-246. doi:10.1159/000076784 7) Macphail, Euan. and Bolhuis, Johan. (2001), Te evolution of intelligence: adap- tive specializations versus general process, Biological Reviews, 76(3), 341–364. 8) Mitchell, Christopher. (2016). Te FALL 2016 | Berkeley Scientifc Journal 49