behavior » The Thinking Meat Project

So what does make humans unique?

Human origins and evolution Comments Off

Mar 312013

I went to hear Dr. Kim Hill's talk on Thursday on the origins of human uniqueness. Hill began by framing our uniqueness in terms of our energy usage and biological dominance&emdash;for example, the fact that we cycle more nitrogen than all other terrestrial lifeforms combined, and we represent 10 times more biomass than any other large species that ever lived. We also exhibit extreme social complexity and specialization; no other species has anything remotely resembling the New York Stock Exchange or the NCAA basketball tournament, for example. Moreover, even before agriculture, we had colonized every landmass, and hunter-gatherers exhibited unusually complex social behavior compared to that of other animals. However, although we exhibit non-unique traits that arose through non-unique processes, we somehow turned into this distinctive species. The question is, how?

Hill described a combination of critical features that enabled all this to happen: cumulative culture, non-kin cooperation, language, and various cognitive capacities. These features emerged from various preadaptations, including bipedality, a change in our dietary niche, and a shift in the human life history (that is, the timing and duration of the events that make up the human lifecycle) and social structures. He focused on a chain of events involving non-kin cooperation and cumulative culture. To illustrate each link in the chain, he used a great deal of data from his own work and that of others with current-day hunter-gatherers in South America and Africa. The story goes roughly like this:

Our feeding niche shifted from collecting foods to extraction and hunting. (Extraction Includes the gathering of roots, nuts, and other things that require some labor or ingenuity to get.)
As a consequence, there was more variation in the quantity of food available each day. This in turn led to daily food sharing. In two hunter-gatherer tribes that he mentioned, nuclear families never keep more than 50% of any type of resource that they acquire. This buffers the variability for everyone day by day and on longer timescales, and provides protection against starvation due to illness or injury.
The result of this is a fourfold difference in adult mortality between humans and chimpanzees. Adult mortality affects the entire life cycle: delaying maturity, delaying senescence, and extending the productive years of adults.
Because maturity is delayed, and children depend on their parents for food, parents have multiple dependent offspring at any one time. As anyone who has bought groceries for a large household can imagine, this is difficult for parents. Several strategies arose to address this problem. One of them is that adults without children, for example, siblings of the parents, may help out (AKA opportunistic cooperative breeding, or helpers in the nest). In fact, the food sharing that arose initially as a way of reducing the variation in the food supply, and thus the risk, became intentional overproduction. That is, people seek out excess, for instance, by gathering more food than they need rather than stopping when they have enough for themselves.
An additional consequence is that women live past their reproductive capacity. That is, women go through menopause.
These cooperative breeding arrangements favored the evolution of prosocial emotions, or investment in the well-being of other people in the same group. In insect colonies, cooperation occurs because the insects are closely related. Hill presented evidence that shows that this is not the case for hunter-gatherer bands: People cooperate and do things for the benefit of others even if they are not related.
Juvenile dependence and the resulting investment of fathers in their children and pair bonding gave rise to a pattern described as the exogamy complex which, in a nutshell, eventually created complex social networks that included people who were not genetically related (e.g., in-laws) that allowed cumulative culture to arise.
Cumulative culture is what happens when you not only learn how to build or use a spear or grinding stone or web page, you figure out a better way to do the job. Although other animals learn things from each other, like learning how to use sticks to dig out termites, none of them build on what they learn and improve on what they have learned. Hill suggested that the shift to large social networks may have been as important as evolved cognition in explaining why we begin to produce cumulative culture in the late Middle Pleistocene 200,000 years ago.

Obviously this leaves out important things like language and brain size and other cool things about how we got to be the way we are. However, it's still a fascinating story of our roots. What struck me in particular is the difference between this and Hobbes's description of life in the natural state as nasty, brutish, and short. The hunter-gatherer societies that he described have a form of income insurance that protects against illness or injury, for example, and the entire system of hunter-gatherer life that he described was nothing like “every man for himself.”

At the end of his lecture, Hill noted that maybe we shouldn't be thinking so much about whether we will ever contact intelligent species in the rest of the universe; perhaps we should be thinking instead about highly cooperative social species. A single intelligent human could never have gotten to the moon alone.

One of the most interesting questions that came up in the Q&A afterword was the question of whether it's likely that there could be one more than one such species per planet. The answer, rather sadly, is probably not. It looks as though the price of our success might have been the extermination of all competitors, even distant ones. Hill estimates that we exterminated at least five other hominin species that could have also followed our trajectory, and right now we seem to be in the process of exterminating the chimpanzees.

You can read more about Prof. Hill's work in this New York Times article.

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How we got to be this way

General, Human origins and evolution Comments Off

Jun 212010

Steven Pinker, in a recent paper in the Proceedings of the National Academy of Sciences, proposes an explanation of how human intelligence evolved. He begins by noting that Charles Darwin had no problem believing that intelligence could be explained by evolutionary theory. However, Alfred Russel Wallace, who arrived at the idea of natural selection around the same time as Darwin, thought that because abstract reasoning would have been of no use to prehistoric humans, intelligence must have been the work of a superior being rather than solely the result of natural processes. Scientists have sided with Darwin, but Wallace’s point about the dubious adaptive value of higher cognitive functions to earlier humans is worth examining. Pinker offers an explanation of how we gained our unique profile of cognitive capabilities.

The explanation rests on two things: the idea that we evolved to fit a cognitive niche, and our capacity for metaphorical abstraction. The concept of a cognitive niche originated with John Tooby and Irven DeVore; the basic idea is that we brought to the evolutionary arms race the rudiments of several characteristics that allowed us to exploit other organisms by reasoning and information-sharing rather than by sheerly physical or chemical means (running faster, producing toxins as plants do, etc.). Once we began to move into this niche, new possibilities opened up, and a host of peculiarly human traits likely co-evolved. Pinker emphasizes three traits: the smarts needed to develop and use tools, the capacity for cooperation with those to whom we are not related, and the capacity for the uniquely human combinatorial system of grammatical language.

He discusses briefly how various quirks of the human organism (for example, our relatively long childhoods and long lives, our cultural differences) could have arisen as a result of the development of these capabilities, and also some of the factors that might have predisposed us toward moving into the cognitive niche (prehensile hands, the inclusion of meat in the diet, living in groups).

This is interesting for several reasons. For one, it’s intuitively appealing (to me, at least) to think of a multitude of interwoven causes for something as complex as human intelligence rather than a single development on which everything else hinged. Also, this theory might explain very nicely why we seem to share some capabilities with other animals, things that were once thought to be uniquely human (compassion for conspecifics, tool use, etc.), but we are the only ones to have such well-developed versions of them and to have them all in combination. Pinker also mentions that we test and fine-tune our strategies on the fly within our own lifetimes rather than relying on the much slower pace of evolutionary change to develop responses to environmental challenges or changes in the organisms we eat or otherwise exploit:

Because humans develop offenses in real time that other organ-
isms can defend themselves against only in evolutionary time,
humans have a tremendous advantage in evolutionary arms races.

This seems to explain why we are uniquely destructive as well, and it gives us (although we should already know this) an extraordinary responsibility.

I was also struck by the following:

The selection pressures that the theory invokes are straight-
forward and do not depend on some highly speciﬁc behavior (e.g.,
using projectile weapons, keeping track of wandering children) or
environment (e.g., a particular change in climate), none of which
were likely to be in place over the millions of years in which modern
humans evolved their large brains and complex tools. Instead it
invokes the intrinsic advantages of know-how, cooperation, and
communication that we recognize uncontroversially in the con-
temporary world.

This seems to sidestep my objections to the way evolutionary psychologists sometimes seek to explain our behavior and the way they assume there was a single environment that definitively shaped everything about us.

You still have to wonder how we developed the ability to understand and use things that our ancestors had no pressing need for (differential equations, the concept of the state). That’s where the idea of metaphorical abstraction comes in. Basically, this means that we are able to take relationships that apply to space and force and then abstract them out to apply to other things. Our language is full of such metaphorical uses; when the Dow goes up, it doesn’t really ascend skyward, for example (although when it falls we do sometimes seem to hear a certain sickening thud). These metaphors reveal that we have pressed various physical concepts into use in novel ways. The power of this is that it allows us to mentally combine and manipulate abstractions. He gives lots of interesting references to the literature on this capability.

The article also offers some insight into how the theory of the cognitive niche could be tested, which I find exciting:

The theory can be tested more rigorously, moreover, using the
family of relatively new techniques that detect “footprints of selection” in the human genome (by, for example, comparing rates of
nonsynonymous and synonymous base pair substitutions or the
amounts of variation in a gene within and across species). The theory predicts that there are many genes that were selected in
the lineage leading to modern humans whose effects are concentrated in intelligence, language, or sociality. Working backward,
it predicts that any genes discovered in modern humans to have
disproportionate effects in intelligence, language, or sociality (that
is, that do not merely affect overall growth or health) will be found to
have been a target of selection. This would differentiate the theory
from those that invoke a single macromutation, or genetic changes
that affected only global properties of the brain like overall size, or
those that attribute all of the complexity and differentiation of
human social, cognitive, or linguistic behavior to cultural evolution.

However, Jerry Coyne, in his blog Why Evolution is True discusses this paper and goes into some very interesting details on why such testing would be difficult.

In short, Pinker’s paper is full of meaty food for thought and discussion, and it also offers a way to look for evidence, problematic though that may be. Fascinating stuff! The entire paper is available online. The full citation is:

Steven Pinker, The cognitive niche: Coevolution of intelligence, sociality, and language. Proceedings of the National Academy of Sciences, May 11, 2010; 107 (Supplement 2): 8993–8999. DOI: 10.1073/pnas.0914630107

Crying

Psychology 1 Response »

Dec 172008

The other day I was struggling with a particularly difficult editing assignment, and when I took a break, I said to a friend that it was so frustrating it made me want to cry. He responded that crying seldom helped anything, with which I disagreed; sometimes I find crying to be therapeutic. “Well, if you must,” he said. In the end I didn’t cry; I grabbed a few munchies and went back to the assignment.

But if only this press release from the Association for Psychological Science had come out a few days earlier, I would have had some research to back me up. Not everyone feels better after crying, but a lot of people do. It’s a short release, and part of it is about the difficulties of studying crying in the lab, which I can certainly believe are considerable. However, it also covers some recent research on crying incidents that happened outside the lab and were later described to researchers. Out of the 3,000 incidents they looked at, most people did report feeling better after crying, although one-third said that they didn’t notice any improvement, and one-tenth reported feeling worse.

So what’s the difference? It’s probably a long complicated story. However, what we know so far includes the fact that of the crying episodes reported, the people who received some emotional support were the most likely to feel better. On the other hand, people who are alexithymic (not as perceptive about their emotional states) tend to feel worse after crying, and those with anxiety or other mood disorders tend not to feel better after crying. I expect there are a host of other variables, like personal history, how often you cry and how comfortable you are with it, who else is around and how they’re feeling. In my own case the other day, perhaps I was unconsciously weighing the variables: getting the assignment done was the thing most likely to bring relief, in those particular circumstances, so I buckled back down to it.

To tie this into the “emotion and music” thread, I’ve got a few CDs that I listen to only when I’m all by myself and not busy with anything that requires concentration, so they can work their full therapeutic magic. Every now and then, for example, I need to put on U2′s All That You Can’t Leave Behind and just let go and cry. Some of the lyrics are emotionally intense, particularly in the song Kite, which is about the death of a parent and which I first heard about six months after my mother died. But the album ends with a gentle, hopeful ballad, and by the end of that song I feel calm and peaceful. For however much I paid for that CD, it’s got to be the cheapest form of therapy.

How thinking meat travels

Being human Comments Off

Aug 262008

OK, this one is off the beaten path, but bear with me. This article from the Wilson Quarterly is about a traffic engineer, Hans Monderman, but it also covers some topics that I think are related to vital thinking meat concepts. Monderman was an advocate of removing the signage and barriers that separate automobile and pedestrian/cyclist traffic; the idea is that if you’re not instilling a possibly illusory sense of safety and containment in drivers, they will be more aware of their surroundings and drive more cautiously. (And in fact there is some evidence that a decrease in signage and a greater integration among the various modes of traffic—cars, pedestrians, and cyclists—can reduce accidents. One thing I know from my many years as an urban walker and from listening to urban cyclists is that staying alive on foot or on a bicycle involves a keen awareness of what the cars surrounding us are doing. It seems to me that one of Monderman’s points was that everyone is safer if drivers are also keenly aware of the presence of pedestrians and bicycles in their midst.)

The article touches on themes like how we perceive space, time, and distance, how we conceptualize danger, and how we alter our behavior based on our surroundings. Given the importance that we as a society have placed on the automobile over the past couple of generations without thinking about or even being aware of all the ramifications of a car-centric society, I think it’s good to look at how things (specifically, our cities and towns) got to be this way and how they might be otherwise. And what the hey, this is the only article on traffic design I’ve run across that mentions the writing of Marcel Proust and John Ruskin. Bound to be interesting, right?

A smiling voice

Psychology 1 Response »

Jan 162008

Wait a minute, shouldn’t that header say “A smiling face”? No; voices can show a smile too. Researchers videotaped test subjects who were answering questions in an increasingly silly interview, and identified on the videotape four different levels of smile, ranging from no smile at all to a full-out grin. Then people who hadn’t seen the video were given just the audio portion to listen to, and it turned out that they were pretty good at identifying the different types of smiles just from characteristics of the voice. Voice communication has emoticons beat when it comes to conveying subtle nuances of emotion, and this is a good example of that. This article from Science Daily has more information.

Imperfect tense

Psychology 1 Response »

Dec 072007

This article from the International Herald-Tribune talks about some recent psychological studies of perfectionists. One of the things I remember hearing when I was growing up was the advice: “When a job is once begun, never leave it till it’s done. Be it great or be it small, do it well or not at all.” For some this may be an inspiration to achievement, but I found it rather daunting, and I’m afraid it left me likely to not do things at all rather than to risk doing them poorly (as people often do when they’re learning a new skill). However, I can’t blame this advice for my reaction to it, because I suspect that it’s my nature to be dissatisfied with myself anyway. I want not only to do things perfectly, but to do them perfectly the first time I try them. I know, I know, this is an unrealistic expectation. But unrealistic expectations are what perfectionism is all about.

The article discusses some research that identifies negative thought patterns associated with depression (e.g., all-or-nothing thinking, which you’ll find listed in books on cognitive behavioral therapy as a no-no). The article also mentions a subdivision of perfectionists into three distinct types. I found this part very useful. I’m definitely the first type, hard on myself and prone to self-critical depression. I also tend to be soft-spoken and verbally gentle, even wimpy, which doesn’t match some stereotypes of the perfectionist as demanding and inflexible. However, those stereotypes may fit the second subtype, those who expect perfection in those around them. (If you are of the first type, spending time around someone of the second type can be seriously demoralizing.) Perfectionists of the third type try to measure up to a standard that they believe others expect of them.

One thing therapists try to do with perfectionists is to get them to loosen up a little bit, let some of the smaller things go, and observe that the world doesn’t stop turning as a result. Hmmm. Maybe I should try that someday. Do you think I’ll get it right the first time I try?

Religion and altruism

Psychology 2 Responses »

Aug 292007

A recent experiment at the University of British Columbia looked at what happens when you prime people with concepts related to either religion or civic responsibility and then have them take part in a game where they have the power to keep or share some money that they are given. Priming involves presenting subjects with a stimulus–in this case, words–that subconsciously influences the direction of their thoughts. The people who were primed with words having to do with religion or with the responsibilities related to our legal system were more generous than those in a control group who were not similarly primed. The effect of the religious priming was the same for those who said they believed in God and those who did not.

The article about this from EurekAlert seems to be saying that thoughts of religion make people behave more generously, but it’s worth noting that evidently thinking about the legal system has the same effect (the prime words for the “civic responsibility” experiment were civic, jury, court, police, and contract). I can understand the need to test the connection between religion and behavior in a lab setting where you can measure and control the variables, but on the other hand this seems so artificial that it’s hard to know what to make of it. It would be interesting to see if people who were primed with the appropriate words would be more generous in a real-life situation requiring donations of their own money or of time, for example. (Isn’t this sort of priming something that people who are trying to raise money for a good cause often try to do? How well does it work for them?) And I wonder about things like whether people drive any more thoughtfully and cooperatively when they are leaving church than they do when leaving the grocery store or their jobs.

The article also mentions a lack of hard data about the relationship between religious belief and moral behavior. Does anyone know of any studies that look at whether the religiously observant behave any better as measured by crime statistics or other measures? I think there was a rather controversial study in 2005 that looked for relationships between various social indicators and rates of religious observance and concluded that people behave better in more secular parts of the US, but I don’t know anything about the quality of that work, and anyway I think it was a statistical analysis of populations, not of individuals.

Zimbardo on heroism

Being human, Psychology Comments Off

Apr 172007

A couple of weeks ago I posted an entry about Philip Zimbardo, a psychologist at Stanford. In 1971 Zimbardo ran the famous (or infamous) Stanford Prison Experiment, in which normal healthy young men were randomly chosen to be either prisoners or guards in a simulated prison. The experiment, which was meant to run for two weeks, was cut short after only six days because of the terrible effects on the subjects. The moral of the story seems to be that even normal decent people can be overcome by bad situations and do inhumane things. In this piece from Edge, Zimbardo talks about the other side of the coin: the ability of some people to resist a bad situation and do the right thing even under pressure, and how we can cultivate that kind of heroism.

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