In the book, The Winner-Take-All Society (1995), Robet H. Frank and Philip J. Cook discuss a hypothetical scenario in which a new genetic technique allows babies to be engineered so that they have a 99% chance of performing 15% better on the standardized tests used in American college admissions, such as the Scholastic Aptitude Test (SAT) without actually being smarter in other contexts.  In 1% of babies so engineered, a severe emotional disability will result.  Frank and Cook speculate that many parents would be willing to risk the odds that an enginnered child would not be among the 1% of offspring who suffer the ontogenetic costs of the procedure.  They further argue that as more people exploit this genetic modification, the emotional pressure on the hold-outs would increase.  Frank and Cook point out that while the genetic change in question might initially be beneficial to individuals who received it, the overall net effect on society would likely be negative, since better individual performance on the SAT, or similar tests, would not benefit society.  Any benefit to individuals would tend to diminish as adoption of the genetic modification became more widespread.

The authors use this scenario to illustrate the sometimes perverse incentives created by what they term, winner-take-all markets, in which relative performance is much more determinative of reward than is absolute performance.  While it is difficult to take seriously the precise scenario that the two authors, both economists, describe, the broader point does have potential relevance.  Any genetic modification of the human genome intended to enhance life prospects is likely to have negative effects in a fraction of those individuals whose genomes have been so modified, and possibly in most or all individuals so treated.  Of comparable importance, the societally-damaging incentive structure described by Frank and Cook for the SAT performance-boosting gene alteration could reasonably be expected to apply to all or most germline modifications intended to enhance relative standing.  Furthermore, even genetic screening techniques, some of which are already employed, have the potential to influence the trajectories of allele frequencies and thereby the evolution of the human population.

Elsewhere (2011a; a more complete exposition of these ideas can be found in: 2011b), Frank has drawn an analogy between biological and economic versions of winner-take-all markets and the unfortunate outcomes at the collective scale.  According to Frank, sexual selection for an attribute such as bull elk antler size (assuming that bull elk antler size is based primarily on sexual and not natural selection) is a biological example in which individual advantages, at least initially, can (I would add, but do not automatically) translate into population level disadvantages.

It remains to seen if human genome engineering can be reliably beneficial on even an individual level, given the pervasive occurrence of pleiotropy and epistasis (broadly-defined), but Frank and Cook may be correct that some parents will be willing to gamble with the lives of their future offspring even if the techniques are not safe in 99% of cases as assumed for the hypothetical scenario described above.  If such options become available in the future, these technological means for perceived phenotype enhancement could significantly alter the trajectory of change in the human gene pool and exemplify the potential for cultural factors and processes to influence human biological evolution.  Based on the recent studies (Tennessen et al., 2012; Nelson et al., 2012 ), discussed in my June post on evmedreview.com (http://evomed.org/?p=1351), that document the extent of rare genetic variants (allele frequency below 0.5%), existing medical, public health, and other culture-based interventions are altering the potency of selection sufficiently to facilitate both extensive population growth and increased diversification of the human gene pool.

The broader issue that Frank and Cook raise is the existence of reciprocal feedbacks between human biology and culture, interpreted broadly as the totality of behaviors, practices, and technological capacities.  On p. 201, they offer the following: “… although Adam Smith’s invisible hand assures that markets do a speedy and efficient job of delivering the goods and services people desire, it tells us nothing about where people’s desires come from in the first place.”  They further the note that culture influences desires and markets influence how culture unfolds, so that markets can influence choices, some of which affect trajectories of child development or other processes or attributes normally regarded as biological.  If they are mostly correct, then it is fair to expect that future human evolution, and the extent and nature of human medical needs, will be strongly affected by the dynamic interactions between biology and culture.

References

Frank, Robert H. and Cook, Philip J. The Winner-Take-All Society: Why the Few at the Top Get So Much More Than the Rest of Us, Penguin Books, New York, 1995. 

Frank, R.H. Economic View: Darwin,the market whiz. New York Times, September 17, 2011. http://www.nytimes.com/2011/09/18/business/darwin-the-market-whiz.html?_r=1

Frank, R.H. The Darwin Ecomomy: Liberty, Competition, and the Common Good. Princeton University Press, 2011.

Tennessen JA, Bigham AW, O’Connor TD, Fu W, Kenny EE, Gravel S, McGee S, Do R,Liu X, Jun G, Kang HM, Jordan D, Leal SM, Gabriel S, Rieder MJ, Abecasis G,Altshuler D, Nickerson DA, Boerwinkle E, Sunyaev S, Bustamante CD, Bamshad MJ,Akey JM; Broad GO; Seattle GO; NHLBI Exome Sequencing Project. Evolution andfunctional impact of rare coding variation from deep sequencing of human exomes. Science. 2012 Jul 6;337(6090):64-9. Epub 2012 May 17. PubMed PMID: 22604720.

Nelson MR, Wegmann D, Ehm MG, Kessner D, St Jean P, Verzilli C, Shen J, Tang Z, Bacanu SA, Fraser D, Warren L, Aponte J, Zawistowski M, Liu X, Zhang H, Zhang Y, Li J, Li Y, Li L, Woollard P, Topp S, Hall MD, Nangle K, Wang J, Abecasis G,Cardon LR, Zöllner S, Whittaker JC, Chissoe SL, Novembre J, Mooser V. Anabundance of rare functional variants in 202 drug target genes sequenced in 14,002 people. Science. 2012 Jul 6;337(6090):100-4. Epub 2012 May 17. PubMedPMID: 22604722.