While I don't completely disagree with this posting emphasizing the importance of random factors, I also want to echo an earlier posting about reproductive fitness. We verge on embarrassing ourselves when we emphasize "selection" as "survival"... this is a common misconception that ought to be clear enough to ecologists.
CLEARLY there is a large skew in the reproductive fitness of human beings, even in developed nations. I doubt this skew is the result of supposedly "selective" pressures listed by many so far (accidents, drug addiction, disease, hunger, etc.). In fact, this skew exists in the face of these kinds of social ills, which turn out to disproportionately affect those whose overall reproductive success is greater. The skew in reproductive fitness can be seen in the statistics about poverty in the U.S.: the rate of poverty among children is radically higher than in the population at large (forgive me for not having exact statistics at hand). There is a clear social trend: in the pursuit of wealth (financial or other forms of prestige and privilege), the average person has fewer children. On some level this difference in reproductive fitness between rich and poor means that we have continual upward mobility, as poor people strive towards wealth, filling the empty spaces left as wealthy people retire. But, thanks to our regressive taxation and inheritance laws, it also means that wealth continues to be concentrated amongst a smaller and smaller portion of people. Interpreting this "selective pressure" becomes dicey. Being a humanist and an optimist I tend to view things as follows... There is really not a whole lot of genetic diversity in important traits that leads to differential social success (this is hard for us to conceive of from our ivory towers but if you think about larger society it is clear that it is difficult to define genetically-mediated traits that might explain wealth). Most of what happens is cultural (getting access to education being the most important), so the selection of socially successful people "out" of the reproductive pool has little effect on our overall gene pool. The phenomenon of who reproduces more is a cultural phenomenon, not a genetic one. We are back to the idea of there being little actual selection (i.e. "random" with potential for drift), but not based on catastrophic accidents but on social "accidents" leading some to be poor and some to be rich, some to get good educations and some to not. Obviously, if you believe that genetically superior people become economically successful and are having fewer children, you will reach the conclusion that selection is making us "less fit" on some level. Let's call this conclusion what it is: EUGENICS. If society is about economic success, continued culling out of motivated or bright people is going to change our genetic makeup, supposedly for the "worse". I don't buy this but it is an argument and conclusion that you have to at least deal with when you think about whether human beings are experiencing selective pressure. Draw your own conclusions... but realize that differential reproduction is going on because of the economic system we have in place. The key question is whether that differential reproduction has a basis in genetically diverse traits. FYI, a lot of my thoughts on this subject emerge from the career I had previous to becoming a graduate student. For 8 years I taught junior high school science in a Brooklyn, NY public school. >90% of my students received free lunch (i.e. they were almost all quite poor). School is a crucible for social success... you can see all too clearly which kids are going to become successful and "break out" of poverty and which kids are not. From what I could tell, cultural factors rather than clear genetic factors seemed to dictate which kids would escape. Let me admit the unscientific nature of that subjective study of ~1000 students, but understand at least where I come to my more humanist inclinations. Chris Jensen Department of Ecology and Evolution Stony Brook University -----Original Message----- From: Ecological Society of America: grants, jobs, news [mailto:[EMAIL PROTECTED] On Behalf Of Linda Perelli Wright Sent: Tuesday, February 14, 2006 1:00 PM To: [email protected] Subject: Re: current natural selection pressures I would argue that the more "natural" forces of natural selection (survival on account of resistance to disease/infection, better hunting capabilities, avoidance of obviously fatal situations) may be working only in non-developed (are there any?) or early-developing countries. In highly developed countries, selection seems to be quite random -- survival being mostly attributable to being in the right places at the right times (being near a hospital during a heart attack, being just off the path of the drunk driver, NOT being the customer served the salad with the e-coli, NOT having been born and raised in carcinogenic surroundings, etc.) We all like to think because we're smart (or think we are), we have some kind of edge, but I just don't see it. Maybe I'm one of those who just THINKS I'm smart...... Cheers - Linda Perelli Wright Director of Special Projects Fitzgerald & Halliday, Inc. -----Original Message----- From: Ecological Society of America: grants, jobs, news [mailto:[EMAIL PROTECTED] On Behalf Of Kristina Pendergrass Sent: Tuesday, February 14, 2006 8:33 AM To: [email protected] Subject: Re: current natural selection pressures I guess the question is whether these or other-mentioned modern alternatives are really affecting selection (as in decreasing reproductive fitness) or are simply having an effect on mortality... Kristina Pendergrass > How about modern alternatives to big predators such as traffic, > accidents with tools etc, abuse of alcohol and drugs, or a combination > of all of the above? I would say that in these modern times, there is > still plenty of possibilities to get hurt. > > Jasja Dekker > > PhD student > Resource Ecology Group > Dept. Environmental Sciences, Wageningen University > > On 2/10/06 11:01 AM, "Buffington, Matt" <[EMAIL PROTECTED]> wrote: > >> This is another very broad question that has been bothering me lately. > >> = Are there any current natural selective pressures on humans? I'd >> say = this is mainly for developed countries. I see lots of people >> that are = old enough to reproduce that never would have long ago. I >> hesisate to = list things that may have led to an early dimise but >> there are lots of = them. As far as I know, there are no lions, >> bears > >> or wolves hanging out = in my office building waiting to pounce on >> the > >> old, very young, infirm, = or stupid. Just curious. >> =20 >> Matt Buffington >> Indianapolis, IN >
