From orca midwifery to altruistic rats, 2015 has been an epic year for animal cognition research-- via lab experiments and field observations. Here is my very subjective list of the ten coolest findings in animal cognition this year!

1. Chicks place low numbers on the left

Chicks, just like humans, have an innate mental "number line" where low numbers are on the left and high numbers are on the right. Researchers, who published in Science, found that chicks given a "target" number, such as 5, associated small numbers with a space to the left and larger numbers with the right. This is extremely cool because it suggests that a human's left-to-right mental number line is evolutionarily ancient, an oddity of the brain far older than humanity.

2.Rats dream about their future goals

When scientists showed rats some food in a location they could not reach, then led the rats to rest in a separate room, the rats dreamt about reaching the food. Activity in the hippocampus-- hippocampal "place" cells, specifically-- indicates that the rats formed a mental simulation of their walk to retrieve the food. (Note that in humans, the hippocampus helps us imagine the future). This demonstrates that we are not the only animals to plan for the future, to internally rehearse future action, and indeed to dream.

3. Bonobos speak with homonyms

Bonobos-- our peaceful great ape cousins-- use the same sound to evoke a variety of different meanings, Humans do that too-- we call such sounds "homonyms" (e.g., bark on a tree; bark of a dog). In the original article, the researchers call this ability "functional flexibility," a necessary precursor to the development of complex language. The alternative-- functional fixation-- was thought to be a trait of all non-human animals, who were presumed to vocalize only in response to emotional states (a loud yell for fear or anger, a gentle peep for calm). This research closes a formerly presumed chasm between humans and our primate relatives.

4. Orcas seem to act as midwives

When a baby orca was born in Seattle with strange bite marks on its dorsal fin, then observed with a female too old to be its mother, researchers came up with a nigh-unbelievable conclusion: the adult female orca assisted with the birth, helping to pull the baby out of its mother, then "babysitting" the kid to give the new mom a rest. While this may seem far-fetched, remember that this comes from a species with an "astounding potential for intelligence."  Further, recent research demonstrated that menopausal killer whale females provide many helpful services for their pods, such as remembering vast stores of useful information (like where food can be found). Might not one of their services be midwifery?

5. Forest birds have an interspecies alarm call system

Forest species have a vast interconnected network that warns of predator approach. Birds and squirrels sight predators and give calls of alarm, which then travel through the woods-- via the mouths of many species-- at over 100 mph. Recall that plants communicate with each other via a vast subterranean fungal "internet," and Earth seems more and more like a planet from Avatar with every passing minute.

6. Fish are sentient and feel pain

In a comprehensive review published in Animal Cognition, Culum Brown finally laid rest to claims that fish don't feel pain and should not be afforded the same protections as other vertebrates. The author writes, "The review reveals that fish perception and cognitive abilities often match or exceed other vertebrates. ... the evidence for pain perception strongly suggests that fish experience pain in a manner similar to the rest of the vertebrates. ...the extensive evidence of fish behavioural and cognitive sophistication and pain perception suggests that best practice would be to lend fish the same level of protection as any other vertebrate."

7. Crows give gifts to the girl who feeds them

A girl in Seattle feeds the neighborhood crows, who have brought her an array of gifts in return: buttons, beads, paper-clips, and more. When her mom lost a lens cap in a nearby alley, the crows retrieved it, washed it, and returned it. For more examples of crows giving gifts to kind humans (or taking revenge on cruel ones!), read Gifts of the Crow: How Perception, Emotion, and Thought Allow Smart Birds to Behave Like Humans.

8. Bird spouses talk through their marital difficulties

When one member of a pair of zebra finches gets back late to the nest (shirking his duties), the two talk it out via a vocal duet. (Note that zebra finches are good parents who split time on the nest equally-- the late partner was late because curious researchers intervened!) Amazingly, the more the pair talked it out-- the more the male invested in their "talk session--", the better they resolved the problem. If he gave only a halfhearted attempt, less than 40 calls, the female stayed out late during her foraging session, too. In other words, a mistake doesn't matter as much as your effort to work through it together! 

9. Chimps describe trees where good fruit can be found

In the journal Animal Behaviour, researchers described a remarkable discovery about chimp vocalizations: they not only have calls for certain types of food, but describe characteristics of the trees where the food can be found. Specifically, deeper calls referred to bigger trees, while higher-pitched calls describe smaller ones. This indicates that non-human communication can be more nuanced than we thought, and suggests that food played an important role in the evolution of language in our ancestors.

10. Rats choose to save a drowning friend over receiving chocolate

Rats get a bad rap as supposed bearers of disease and infiltrators of our homes. But in a heart-warming study in Animal Cognitionresearchers found that rats will give up a chance at chocolate to instead rescue a friend from having to tread water (the rats were not in actual danger of drowning). And the rats didn't do it selfishly, because they wanted companionship-- they only opened the "rescue" door (letting the rat in their compartment) when the other rat was distressed. Maybe rats aren't so bad after all.

Happy New Year!