Hunter vs. farmer hypothesis

The hunter vs. farmer hypothesis states that attention-deficit hyperactivity disorder (ADHD) in children and its counterpart in adults, the adult attention deficit hyperactivity disorder, have their origins in a tendency in those individuals for behaviors characteristic of hunter-gatherer societies over those of farming societies. The hypothesis was proposed by Thom Hartmann and suggest that these conditions may be a result of a form of adaptive behavior.

Hartmann developed the hunter vs. farmer idea as a mental model after his own son was disheartened following a diagnosis of ADHD, stating, "It's not hard science, and was never intended to be."[1] However, more recent molecular and clinical research has given support to the hunter vs. farmer hypothesis,[2] and some researchers[3] use the hunter vs. farmer idea as a working hypothesis of the origin of ADHD.

Hartmann notes that most or all humans were nomadic hunter-gatherers for hundreds of thousands of years, but that this standard gradually changed as agriculture developed in most societies, and more people worldwide became farmers. Over many years, most humans adapted to farming cultures, but Hartmann speculates that people with ADHD retained some of the older hunter characteristics.

A key component of the hypothesis is that the proposed "hyperfocus" aspect of ADHD is a gift or benefit under appropriate circumstances. The hypothesis also explains the distractibility factor in ADHD individuals and their short attention span for subject matter that does not trigger hyperfocus, along with various other characteristics such as apathy towards social norms, poor planning and organizing ability, distorted sense of time, impatience, attraction to variety or novelty or excitement, and impulsiveness. It is argued that in the hunter-gatherer cultures that preceded farming societies, hunters needed hyperfocus more than gatherers.

Nomadic populations

A genetic variant associated with ADHD has been found at higher frequency in more nomadic populations and those with more of a history of migration.[4] Consistent with this the health status of nomadic Ariaal men was higher if they had the ADHD associated genetic variant (7R alleles). However in recently sedentary (non-nomadic) Ariaal those with 7R alleles seemed to have slightly worse health.[5]

Science and the Hunter vs. Farmer hypothesis

The hunter vs. farmer hypothesis proposes that the high frequency of ADHD in contemporary settings "represents otherwise normal behavioral strategies that become maladaptive in such evolutionarily novel environments as the formal school classroom." An important view, with considerable genetic backing, is that some of these genetic variants may have value in certain kinds of social groups, such as those that have migrated.[6][7] Genetic variants conferring susceptibility to ADHD are very frequent—implying that the trait had provided selective advantage in the past.[3]

A 2008 New Scientist article by Tim Callaway[8] reports that research of ADHD and related traits in different cultures offers some support for the hunter vs. farmer hypothesis. According to evolutionary anthropologist Ben Campbell of the University of Wisconsin–Milwaukee, studies of the Ariaal, an isolated nomadic group in Kenya, suggest that hyperactivity and impulsivity—key traits of ADHD—have distinct advantages to nomadic peoples. Additionally, nomadic Ariaal have high rates of a genetic mutation linked to ADHD, while more settled Ariaal populations have lower rates of this mutation. Henry Harpending of the University of Utah reports that with this genetic mutation, "You probably do better in a context of aggressive competition."

See also

References

  1. ↑ Hartmann, Thom (1995). ADD Success Stories. Grass Valley, California: Underwood Books. xvii. ISBN 1-887424-04-0.
  2. ↑ Arcos-Burgos M, Acosta MT; Acosta, Maria Teresa (June 2007). "Tuning major gene variants conditioning human behavior: the anachronism of ADHD". Curr. Opin. Genet. Dev. 17 (3): 234–8. doi:10.1016/j.gde.2007.04.011. PMID 17467976.
  3. 1 2 Arcos-Burgos, M.; Acosta, M. T. (2007). "Tuning major gene variants conditioning human behavior: The anachronism of ADHD". Current Opinion in Genetics & Development 17 (3): 234–238. doi:10.1016/j.gde.2007.04.011. PMID 17467976.
  4. ↑ Chen CS, Burton M, Greenberger E, Dmitrieva J (September 1999). "Population migration and the variation of dopamine D4 receptor (DRD4) allele frequencies around the globe". Evolution and Human Behavior 20 (5): 309–324. doi:10.1016/S1090-5138(99)00015-X.
  5. ↑ Kiaris, Hippokratis. (1 April 2012). Genes, polymorphisms, and the making of societies : how genetic behavioral traits influence human culture. Boca Raton: Universal-Publishers. pp. 80–83. ISBN 978-1-61233-093-8.
  6. ↑ Chang, F. M.; Kidd, J. R.; Livak, K. J.; Pakstis, A. J.; Kidd, K. K. (1996). "The world-wide distribution of allele frequencies at the human dopamine D4 receptor locus". Human Genetics 98 (1): 91–101. doi:10.1007/s004390050166. PMID 8682515.
  7. ↑ Grady, D. L.; Chi, H. -C.; Ding, Y. -C.; Smith, M.; Wang, E.; Schuck, S.; Flodman, P.; Spence, M. A.; et al. (2003). "High prevalence of rare dopamine receptor D4 alleles in children diagnosed with attention-deficit hyperactivity disorder". Molecular Psychiatry 8 (5): 536–545. doi:10.1038/sj.mp.4001350. PMID 12808433.
  8. ↑ Ewen Callaway (June 10, 2008). "Did hyperactivity evolve as a survival aid for nomads?". New Scientist.

External links

Further reading

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