Cognition in nonhuman animals
Contagious yawning has been experimentally demonstrated in humans, dogs, chimpanzees, and baboons.
Horses have been experimentally demonstrated to be able to anticipate their comfort in the future and use symbol boards to communicate their preferences accordingly.
Dogs are capable of recognizing their own scent in unfamiliar situations and will spend substantially less time investigating it, a difference that develops with age, which has been cited as evidence of a capacity for self-recognition. They also experience contagious yawning with other dogs and humans, with a bias towards familiar humans, indicating some empathic capacity.
Notable individuals: Hoover
Notable individuals: Melanie
When Asian elephants (Elephas maximus) were tested, one individual (a female named Happy) investigated a mark made on her head using the mirror, and did not investigate a similar mark made with colorless paint.
Alex the grey parrot and zero
At least one individual, [Alex], was observed practicing words when alone.
Magpie grieving rituals
New Caledonian crows (Corvus moneduloides) demonstrate simple tool use, and even modifying flexible material (such as leaves and wire) into hooks. Common ravens (Corvus corax) have been observed anticipating observation by unseen competitors when caching food, which has been argued to be evidence of a theory of mind.
Eurasian magpies (Pica pica) pass the mirror self-recognition test.
Monk Parakeets surviving in Chicago despite climate
Cleaner Wrasses were the first fish to pass the mirror test. They also appear to have some degree of , and have the unusual distinction of improving other species' cognitive abilities through their parasite removal behavior.
The Giant oceanic manta ray (Manta birostris) did not engage in social behaviors when presented with a mirror, instead engaging in unusual and repetitive movements that may be self-examination. Rays have exceptionally large and well-developed brains for their size, supporting an intelligence reflected across many behavior tests.
Daffodil chichlids (Neolamprologus pulcher), when subjected to mirror testing, acclimated to their mirror images but did not appear to investigate marks on themselves.
Bees are capable of observational learning, and can count and recognize quantities up to four. They are also able to grasp zero as a quantity and order it lower than one in a counting sequence.
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- Grief in animals: It's arrogant to think we're the only animals who mourn by Marc Bekoff Ph.D., Psychology Today, October 29, 2009
- Elephants Mourn Loss of "Elephant Whisperer" Lawrence Anthony by Marc Bekoff Ph.D., Psychology Today, March 07, 2012
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- Ravens' fear of unseen snoopers hints they have theory of mind, Sam Wong, New Scientist, 2016-02-02
- The Fish That Makes Other Fish Smarter by Ed Yong, The Atlantic, March 07, 2018
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- Manta ray brainpower blows other fish out of the water by Amy McDermott, Oceana, 2017-07-25
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- Scarlett R. Howard, Aurore Avarguès-Weber2, Jair E. Garcia1, Andrew D. Greentree, Adrian G. Dyer. (June 2018). "Numerical ordering of zero in honey bees". Science. 360(6393): 1124-1126. doi: