Continuing with evolutionary approach to psychology…

It is now widely accepted that human beings (and all other organisms) came about through a series of gradual changes in a common ancestor. Individuals in a species exhibit variability that has some genetic basis—heritable. If those variations lead to enhanced reproductive success, those trait variants will be more highly represented in subsequent generations—eventually, variability in that trait will disappear, as all members of the species come to possess that trait. We can think of this as the mechanism that underlies the human universal psychology that we discussed earlier in the semester, and what I hope to do today is to demonstrate that some universal psychological traits are not even specific to humans…they may have been something shared by our closest evolutionary relatives.

So basically, in order for an individual to pass on their genes, they MUST survive—therefore, natural selection has provided us with hard-wired, purely genetically determined tendencies for survival-related behaviors that are very hard to break. We MUST eat, for example…it takes really extreme environmental circumstances for us to voluntarily forgo food. And when we are deprived food when we want it, it makes us really, really cranky. Babies are born knowing how to eat. Quite simply, because those that didn’t, or weren’t motivated to, find sources of sustenance didn’t survive to reproductive age. Evolution has also equipped us with certain psychological mechanisms like fear—and we have very well developed mechanisms for mobilizing our resources when we’re under stress. These traits are all those that helped us to survive in our ancestral environment. But survival isn’t the whole story, we MUST reproduce. And behaviors involved in attracting mates are also universal across cultures, no matter what the environmental context.

So, basically, when we see behaviors that are universal across cultures, and importantly, behaviors that are shared with our closest evolutionary relatives, we suspect that they were useful for survival and reproduction.

Now, who are our closest evolutionary ancestors??

Diamond chapter 1—DNA hybridization techniques, allow us to determine the relationships among primate species…Let me clarify what it means to be closely related to another organism in terms of shared ancestry. You and your siblings are closely related because you share an ancestor in the last generation—namely your parents. You and your 2^nd cousins are related less closely than siblings because you share an ancestor 2 generations ago. We human beings are all related to one another because we all descending from a common ancestor who lived roughly 1000 generations ago…the first population of homo sapiens that arose in Africa roughly 200000 years ago gave rise to all human beings alive today. That’s they way you can think about relatedness in terms of common ancestry among members of the same species and even among species. These days one can just compare genome sequences using big computers—this is the kind of brute force number crunching task computers are good at. But it wasn’t always this easy, in the days before the Genome Projects identified the sequence of human and other animals DNA. The basic idea is to take DNA strands from each species…denature it and allow mixed DNA from the 2 species to combine. Hybrid DNA will be a looser fit…how loose depends on how closely related the two species are. This kind of analysis suggests that humans and chimps share 98.4% of their DNA. Chimps and Gorillas share less DNA than that…suggesting that not only are chimps humans closest relatives, but humans are chimps closest relatives. Knowing degree of similarity, we may also figure out years since the divergence occurred…need a way to determine how long it takes DNA to change…a molecular clock. Calibrate for 2 species with known age of common ancestor. We now know through genome comparisons that humans and chimpanzees share 96% of their DNA but the estimate of a common ancestor roughly 6 million years ago is still the primary estimate.

Part of evolutionary psychological thinking is to try to understand the behavioral tendencies that all humans share by trying to figure out what the survival benefit of particular traits is or may have been during our evolution. Of course, some of these traits may be those that were present before humans and chimpanzees diverged from the common ancestor. If so, we would expect them to be present in our closest primate relatives. Perhaps one of the most interesting applications of this kind of thinking comes from considerations of why we have minds at all—the conscious, self-awareness that is so much a part of human experience. Do other animals also have a self-concept, an appreciation of the self as a distinct entity? All animals are capable of sensing their environments and, we believe, creating a conscious representation of the environment—although keep in mind that this is impossible to know for sure. But do other animals create a conscious representation of themselves? How on earth could we know that?

How can we tell that an animal is self-aware? Well, the gold standard in research for determining self-awareness is whether an organism can become an object of its own attention…mark test (mark-directed behavior on self after dye is placed on forehead—animal must be capable of understanding mirrors).

Who passes the mark test?

Chimpanzees

Orangutans

One gorilla

Human children > 18 months

Well, if it’s true that some apes have self-awareness, a sense of self, a recognition of the self as an object, why might this property have evolved? So, let’s try to engage in a bit of an evolutionary or functional explanation of self-awareness? What functions might it have served during the course of evolution? Why might animals that had a self-concept survived? It might be relevant that chimps, animals who very frequently pass the mark test have been observed to engage in behaviors like deception, politicking, they can very clearly negotiate complex social relationships…this ability may have been pretty important to these animals, and most of the going theories on how self-awareness evolved focused on not only awareness of self, but awareness of other. Consideration of living in groups (need to be able to plan your actions and anticipate their effects)…therefore, social theories of the evolution of self-awareness is one of the more common types of hypotheses…but there are some flaws with these types of hypotheses.

-don’t seem to understand concept of other—many studies (elaborated in the Povinelli article) demonstrate that apes do not have a “theory of mind”

-monkeys navigate social situations and don’t pass mark test

-some solitary animals pass the mark test (such as orangutans)