Reddit mentions of Mothers and Others: The Evolutionary Origins of Mutual Understanding

We have a very good understanding of their intelligence. They are probably some of the most well studied species in terms of behaviour and cognitive abilities on this planet. In ELI5/TLDR* most researchers would characterize their intelligence of being equivalent to a 2-3 year old human child. Just a short list of things that characterize these species:

• They form long-term social bonds and remember individuals
  
  
• They are able to recognize self from other
  
  
• They are able to lie
  
  
• They are able to understand fairness
  
  
• They are able to make, modify and use tools
  
  
• They have culture and tradition
  
  
• They are able to demonstrate empathy
  
  
• They feel the same or similar emotions to humans
  
  
• They have morals
  
  
• They mourn the dead
  
  
• They are able to solve multi-step problems
  
  ...
  
  I suppose another way of looking at this is what do we have that they lack. What makes humans unique?
  
  We know of some factors that contributed to our awareness and unique intelligence as compared to other living species. It is important to know that this is a very active area of study in many different disciplines (psychology, biology, animal behaviour, psychiatry, physiology, anthropology, neurology, linguistics, genetics, archeology...).
  
  
• Traits we inherited from our distant ancestors. Obviously all species are a cumulation of inherited traits. Who we are today is largely due to who "we" were in the distant past. We inherited a strong tendency to be a very social species from our mammalian ancestry. Mammals are social beings, humans included. We inherited opposable thumbs from our early primate ancestors. Humans are not the only species with opposable thumbs so it is not a trait that is unique to our species. However, the inheritance of thumbs enabled us and the other primates to develop fine motor skills like precision grip. This enables us to manipulate objects, and make/modify tools. Humans also inherited an upright bipedal posture from our early ancestors. Humans are not the only bipedal species (after all, all birds are bipedal!) but our upright posture has given us many advantages, namely that it frees our hands to do other tasks.
  
  
• Brain/body size ratio & exceptional brain gyrification is a somewhat useful indicator of how intelligence a species is. The correlation is decent among related mammal species, but it breaks down when applied to distantly related animals. It underestimates intelligence in heavy animals like horses and overestimates small animals like mice and birds. You also have to consider what the animal's brain has evolved for. Bird's typically have very large brains for their body but may not be exceptionally smart. A lot of that large bird brain is used for flight calculations and isn't available for higher level processing. Fruit flies have enormous brains compared to their mass, but that brain is simply too small to have any real thought processes. Humans are highly intelligent because they have an extremely large brain for their normal body mass and that brain has evolved specifically to perform complex thought. Size isn't the only factor, scientists also consider the degree of specialization, complexity of neural connections, and degree of brain gyrification. Humans score high on all these physical qualifiers associated with increased intelligence.
  
  
• Two cognitive traits thought to be unique to humans - shared intentionality and cumulative culture. Shared intentionality goes one step further than being able to solve problems as a group, it involves anticipating the needs of others and the situation in order to solve a common goal. This requires incredible foresight, flexibility, and problem solving skills. It requires an almost hyper-sociality group structure. We couldn't stick 100 chimpanzees on a plane and expect it to land in one piece...but you can stick 100 human strangers and all, for the most part, get along just fine. This level of cooperation is rarely seen among other animals (save for the Eusocial insects, naked mole rats, and perhaps Callitrichid monkeys)...my point is we have a shared intentionality that allows us to be hyper-social and cooperative. Cumulative culture goes beyond the cultures exhibited by other animals. Other animals have culture where [non-essential] traditions are passed on from one generation to the next and can be modified slowly over many generations. Humans also have traditions, but these are past on much more easily between individuals. Moreover, these traditions are quickly modified, almost unlimited times within a generation. We are able to rapidly build upon the ideas of others and modify these ideas to suit new problems. Moreover, our adults, as compared to the adults of other species, are much better at learning and retaining new skills or traditions. Generally speaking, the age old adage "you can't teach an old dog new tricks" applies well to the non-human animal kingdom.
  
  These two traits, shared intentionality and cumulative culture, led to the development of other aspects of our being which are unique (e.g language). Everything else that we can do is just a happy by-product of these two traits: being able to go to the moon, or build a super dam, or create art, or think in the abstract, maths, industrial agriculture...Those things are by-products of our level of cognition. Our uniqueness is derived from shared intentionality and cumulative culture plus a couple of random physical traits that we were lucky enough to inherit from our distant ancestors - a big brain, bipedalism, and opposable thumbs. We are not the only species with a large brain-to-body ratio, we are not the only bipedal species, and we are certainly not the only species with opposable thumbs - these are physical characteristics that we inherited from our distant primate ancestors. These traits built the foundation for what was to come.
  
  Whatever the pressure around 40,000-50,000 years ago we notice a significant shift in the archeological record. All of a sudden humans are making cave art, our hunting tools are changing rapidly, we began to engage in long distant trade, we made jewellery and we even had symbolic figures - perhaps the seeds of language. This is known as the period of behavioural modernity. Not only did these humans look like us, they acted like us too. Its hypothesized that an infant from this time could be raised in a modern context with little to no intellectual deficit...we wouldn't be able to pick them out of a crowd. Humans haven't gotten more intelligent over time. It is hypothesized that a human from 50,000 years ago is anatomically and behaviourally modern.
  
  So, if we aren't any smarter - why do we have cell phones and galaxy print jeggings and people didn't way back then? Increasing complexity - we know more than people in the past because we've built upon what they've learned. Humans have always been smart, and our great benefit is that we build on other people's discoveries. Someone figured out how to domesticate plants, someone figured out how to sew cloth, someone figured out how to weave materials, someone figured out synthetic materials and dyes, someone put it all together in those jeggings. We just build on what other people have found out. This is cumulative culture in action. Humans today are not more intelligent than humans living 50,000 years ago - we both have the same potential. The difference between us and them is we have a wealth of shared knowledge to draw upon, and they did not. Humans 5000 years from now could be asking the very same question..."Why didn't they invent warp travel, its so easy!"...well we don't have the wealth of another 5000 years of experience and scientific study to draw upon. We only have what our ancestors gave us. As more and more knowledge is accumulated we should in theory progress faster and faster.
  
  Some interesting books on the subject:
  
  Age of Empathy
  
  Our inner ape
  
  Moral lives of animals
  
  Affective neuroscience
  
  Mothers and others
  
  

This is such a great question! One that we have been trying to answer for as long as people have had thought. For a very long time we had a set of traits and behaviours that we thought were unique to humans, that set us apart and above from all the other animals. This list is getting smaller and contains more caveats as time goes on. It wasn't long ago that we thought humans were the only tool makers, only to be shown that tool making & modification is pretty pervasive throughout the animal kingdom.

There are three things that set us apart from other animals and that are truly unique to our species (in so far as we understand today):

1. Aspects of language
   
2. Shared intentionality
   
3. Cumulative culture
   
   Language isn't completely unique to us. Many aspects of complex language thought once to be only found in humans have been described in animal communication. For example, there are a growing number of species known to us that make specific calls for specific situations. Some monkeys will make a specific call for a land predator like a jaguar vs. a sky predator like a hawk. Some species have even demonstrated rudimentary syntax. Finally, calls are also used to convey complex states or ideas - for example some species are able to use their calls to deceive (which is a very advanced cognitive ability in of itself). They make a warning call to distract the group while they sneak off and get some tasty piece of food that they otherwise would have had to compete for. We are really only beginning to scratch the surface of animal communication and the more we discover the more we realize just how complex their communication systems can be. It can't be denied that other species lack a certain "something" that we seem to have. They aren't able to communicate quite like us, but to say that animals lack language outright is to do a disservice to the complexity of language that they do have.
   
   Cooperation is seen throughout the animal kingdom in abundance. Animals cooperate all the time, especially social animals like primates. In fact there are some species that are so reliant on cooperation that they can't survive or breed without it. These animals are called cooperative breeders. Species like naked mole rats, meerkats, bees, and callitrichid monkeys require the aid of others to help raise their offspring. Other individuals in the group will forgo their own breeding to insure the survival of the dominant pair's offspring. A great novel on this subject is called Mothers and Others. There are many great experiments that require the cooperation of two individuals to solve, these have been successfully completed by many different species of monkeys and apes as well as non-primate species like elephants. In addition many species hunt in groups that requires significant cooperation and coordination. A lone wolf isn't going to take down a great big bison, they need to cooperate in order to take down their next prey. But again, there is something that is unique about the way humans cooperate, and this is more accurately referred to as shared intentionality*.* Humans can visualize a common goal and cooperatively work towards that goal. "Shared intentionality, sometimes called ‘we’ intentionality, refers to collaborative interactions in which participants share psychological states with one another...For example, in problem- solving activities participants may have a shared goal and shared action plans for pursuing that goal, and in communication they may simply share experience with one another linguistically. The big Vygotskian idea is that what makes human cognition different is not more individual brainpower, but rather the ability of humans to learn through other persons and their artifacts, and to collaborate with others in collective activities (Tomasello, 1999; Tomasello, Carpenter, Call, Behne & Moll, 2005a; Tomasello, Kruger & Ratner, 1993)." Its a step up from the classical cooperation we see in animals. Its the reason why 150 human strangers can get on a plane and cooperate and why 150 animals that were strangers could not.
   
   Finally, the last trait that is unique to humans (although newer research may be demonstrating this in some primate species) is cumulative culture*.* Humans have the unique ability to not only share psychological states we have the ability to store intergenerational information and share that information quickly and efficiently with others. This information can be rapidly dispersed through a group (or between groups) and is quickly passed on from one generation to another. Now, we know that animals share all sorts of information and that individuals do learn from each other. For example, a single female Japanese Macaque decide to start washing her potatoes in the sea. Within a vert short period of time nearly everyone, but especially the young individuals, were washing their potatoes too. Over successive generations different washing techniques have been added in, and even different foods are washed. But its a great example of a single individual introducing a new behaviour to a group which suddenly spreads amongst all its individuals. Its a great example of animals having a distinct culture. But humans just take this to the next level. Where it takes years or even decades for a chimpanzee to master the use tools requires to get termites out of a termite mound it would take humans seconds. Moreover, most animals can only learn these complex behaviour if they are taught or observe these behaviours while they are young. Adult humans are much better at picking up new traits, behaviours, and skills as compared to other adult animals. We simply are faster at sharing and absorbing information and this has led to our unique trait of cumulative culture.
   
   The actual physiological mechanisms that allow these things to happen are unknown. We don't know how or why we evolved these traits. No genes have been identified. We don't even have a clear idea when these traits evolved within our own species. All we know is that we seem to have them and they do not, which is why we have gone to the moon, have complex maths, and galaxy print jeggings and they do not.

I agree with a lot of your article, but you're making a huge intuitive leap from "there's danger in not being able to adequately decode another's expression of emotion" to "we're hard-wired to be hostile." There's actually ample evidence that we're hard-wired to be just the opposite: cooperative, accommodating, and generally kind to one another.

Here's an article published recently on the subject. And if you ever have time, pick up a copy of Sarah Hrdy's Mothers and Others: The Evolutionary Origins of Mutual Understanding -- it's the best book I've read in years, and it explores these concepts in incredible depth and breadth.