Attention Deficit Hyperactivity Disorder: An Evolutionary and Cognitive Advantage Edward C. Liu
University of California, Santa Barbara
Was attention deficit hyperactivity disorder (ADHD) an evolutionary survival asset for our ancestors of the hunter-gatherer society? ADHD is a problem with inattentiveness, over-activity, impulsivity, or a combination of the two traits (CDC 2007:1). New studies have shown that prevalence of ADHD in children is increasing every year. For example, a study conducted by the Center of Disease Control and Prevention shows that that rates of the disorder have jumped by 24% since 2001 and those children as young as three years of age are diagnosed with ADHD (CDC 2007:1). Though our society has a substantial amount of knowledge about the diagnosis of ADHD, the functions of the disorder are still uncertain. In fact, recent findings have found that a specific dopamine receptor, the DRD4 7R allele, is associated with ADHD (Hartmann 2007:2). The findings have lead scientist to believe that ADHD is an evolutionary survival asset, but the answer remains unclear. To understand the phenomenon, we must consider the social and ecological environment in which our ancestors from the hunter-gatherer society may have experienced. Hence, the following paper examines ADHD as an evolutionary survival asset in pre-historic times and how it provides certain cognitive strengths to our children with ADHD. Thom Hartmann was one of the researchers who raised the topic of ADHD as an evolutionary survival asset. After conducting extensive research on ADHD during his undergraduate and post-graduate years, he noticed that children with ADHD had very similar traits of an exceptional hunter (Hartmann 2007:2). For example, children with the disorder found repetitive tasks boring and this behavior was reflected in a nomadic hunter who despises mundane task and craves for novelty. Hartmann eventually created the Hunter versus Farmer Hypothesis, which states that all humans were nomadic hunter-gatherers for thousands of years but due to societal changes that led humans to adapt to agriculture, more people became farmers (Hartmann 2007:2). However, humans with ADHD, or the “hunters”, retained some of their primitive characteristics, such distractibility. Meanwhile, the “farmers”, or the people who were able to adapt the agricultural society, became more focused, organized, and patient. Also, previous research had supported Hartmann’s hypothesis in that the DRD4 7R allele are more likely to be found in cultures that are nomadic. A recent study has suggested that the ADHD genotype is an evolutionary asset. Burgos and Acosta (2007) conducted a meta-analysis on genetics and clinical journals that examined ADHD as a genetic and evolutionary asset to human behavior. They gathered journals that examined the following factors: (1) ADHD phenotype: categorical versus continuous, (2) ADHD genetic and association studies, (3) Allelic variants that are susceptible to ADHD. The researchers’ findings concluded that the ADHD phenotype represents a very common behavioral variant in nomadic populations. Burgos and Acosta also concluded that the disorder has provided our prehistoric ancestors because it increased their chances of survival and sexual reproduction. (E.g. faster response to predators, best hunting performance, more effective territorial defense and improvement of capacity for mobility and settling. Therefore, it was not uncommon that humans to be highly susceptible to ADHD due to their genetic makeup, especially in nomadic populations. Burgos and Acosta also noted that there are other theories that may explain the high genetic variation in population (Burgos et al 2007:235). One of the examples they described was the Hartmann’s Hunter-Farmer hypothesis. A limitation of the study is the author’s usage of words and number that may make it harder for readers to comprehend. Recent studies have shown that the DRD4 7R allele...
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