The purpose of this website is to introduce the visitor to the idea that autism, and many other neurological conditions characterized by maturational delay, have their origins in evolutionary processes. When these processes are understood, actions to address the condition can be intuited and initiated.

Many forms of autism occur when a specific human physiological/neurological profile which we will refer to here as left spectrum is not provided the specific kind of sensory stimuli craved by individuals with the related tendencies. The profile evolutionarily precedes the present day physiological/ neurological profile by at least 30,000 years, likely as much 100,000 years. It is our conclusion that autism is not a ‘regression’, but an expression of a common though minority contemporary physiological/neurological profile now becoming more prevelant because of specific kinds of influences, largely environmental. This physiological/neurological cluster was the more common type for tens of thousands of years before the rise of patriarchal social structures and the physiological/neurological profile associated with these new cultures.

The majority of individuals in contemporary societies are living within patriarchal or patrifocal social structures and are highly lateralized, narratively focussed, right handed, hierarchically inclined humans which is a deviation from the traditional matrifocal physiological/neurological type characteristics of which are often found in individuals diagnosed as autistic. The traditional matrifocal type features brains that are less lateralized with the two hemispheres often being of similar size, males that are associative thinkers not narratively organized, individuals who are frequently left handed or ambidextrous, and non-hierarchically organized men who are maturationally delayed compared to their patriarchal social structure relations. The human species is spread along a left-right spectrum or arc reaching from the matrifocal, ambidextrous, left-handed, old genetics on the left to the patrifocal, right-handed, newer genetics on the right with most people falling in the center showing features that are a combination of the two. Individuals with a familial history which places them at the left end of this continuum are particularly vulnerable to disorders characterized by maturational delay.

This site will begin with a discussion on evolutionary theory, proceed to outline the origins of autism through an understanding of matrifocal social structures and its place in human evolution, and conclude by specifying the exact reasons autism is becoming common at this time.

Based on the first examination of heterogeneity in parental age effects, it appears that women’s risk for delivering a child who develops autism increases throughout their reproductive years whereas father’s age confers increased risk for autism when mothers are <30, but has little effect when mothers are past age 30. We also calculated that the recent trend towards delayed childbearing contributed approximately a 4.6% increase in autism diagnoses in California over the decade.

In 1998 I posted at sexualselection.org the hypothesis that older mothers will be discovered to be more likely to have autistic children because their testosterone levels are significantly higher. Simon Baron-Cohen conducted a number of studies that concluded that testosterone level in the mothers are directly connected to autistic tendencies. This study by Shelton, Tancredi and Hertz-Picciotto makes perfect sense in the context of mother’s testosterone levels impacting maturation rates, causing autism.

OBJECTIVE: Autism is referred to as cerebral lateralization abnormality. In this study, the possible relationships among handedness, eyedness and nasal cycle in autism have been investigated. MATERIALS AND METHODS: Thirty-seven children with autism and 20 controls were included in the study. The patient group included 27 boys and 10 girls who ranged in age from 5 to 20 years. For hand preference, hand used to write and throw a ball was accepted as dominant hand. For eye preference or dominance, eye used to look through keyhole of a door was accepted as dominant eye. Nasal dominance was assessed by a method of measuring the nasal airflow. RESULTS: The rates of left-handedness and left-eyedness were higher in children with autism compared to normal populations. A majority of children with autism had left nasal dominance. CONCLUSION: Autism and early language impairment may be associated with left handedness, eyedness and nasal dominance. (Dane, S. & Balci, N.(2007). Handedness, eyedness and nasal cycle in children with autism. International Journal of Developmental Neuroscience, 25(4), 223-6.)

Central to my understanding of handedness is Marion Annett’s theory that the left handed are really random handed, along with almost 10% of the right handers in society. What keeps coming to my mind is, if autism is increasing, and those increases are accompanied by estimations that it is just diagnosis that is more universal, then tell me if there are increases in left handedness. If there are increases in the left handed in this society, that suggests that there are increases in random handedness with is very likely the same as saying there are increases in male maturational delay.

If there are increases in both left handedness and autism, perhaps theorists can start offering attention to theories of autism that have to do with our evolutionary origins.

The present study reports preliminary data from two unselected samples of carefully diagnosed autistic subjects (children and adults) and an assessment procedure that includes a large sample of items, appropriate for lower-functioning autistic subjects, with multiple presentations within and between sessions 1 week apart. The study seeks to determine (1) whether a raised incidence of non-right-handedness exists in these samples (2) if so, what constructs best represent this shift in the handedness distribution (i.e., phenotype and CNS substrate) and (3) whether these handedness phenotypes are associated with different levels of cognitive functioning. The results reveal a dramatic shift away from right-handedness in both autistic samples, due to a raised incidence of two phenotypes, manifest left-handedness and ambiguous handedness. The ambiguously handed, who were postulated to represent substantial bilateral CNS pathology due to early brain injury, were found to have much lower intellectual scores in one of the study samples. (Soper, H., Satz, P., Orsini, D. Henry, R. Zvi, J. & Schulman, M. (1986). Handedness patterns in autism suggest subtypes. Journal of Autism and Developmental Disorders, 16, 155-67.)

Uncovering the differences between brain injury autistics and those that are autistic because of combinations of genetic inclinations (random handed with little cerebral lateralization), environmental effects impacting testosterone and estrogen levels of mother and self, and conventional child rearing practices seem vital to coming to understandings. In other words, how does autism created by brain injury differ from autism created by genetics/environment? Are there studies out there experimenting with potential differences? How would you conclude a child is one but not the other? It’s near impossible until we prove how one of the two causes (brain injury vs genetics/environment can be proved.

Developmental coordination disorder affects 5% to 8% of the general population, and about 50% to 60% of these children have a comorbid attention-deficit disorder with hyperactivity and learning disorders. Left-handedness is relatively common among children with dyslexia, learning disabilities, and autism; however, its frequency in children with developmental coordination disorder is less clear. The present study investigated the distribution of hand dominance in 98 children (age range, 5.5-17 years) with developmental coordination disorder compared with their parents or siblings. Thirty children (30.6%) were left-handed and 13 (13.3%) were ambidextrous. The prevalence of left-handedness among their parents and siblings was similar to that of the general population. The results suggest that children with developmental coordination disorder, like children with learning disorders and deficit disorder with hyperactivity, present with higher frequency of left-hand dominance compared with the general population. (Goez, H. & Zelnik, N. (2008). Handedness in patients with developmental coordination disorder. Journal of Child Neurology, 23(2), 151-4.)

Until recently I hypothesized that the relatively common appearance of autism in first born children was that perhaps first borns had more stressful births than later borns, and that this might be a different kind of autism than that which features maturational delay. I estimated one way to tell the difference was if digital abilities in autistic newborns was inhibited suggesting a cerebral palsy like infirmity. This would be different than the kind of autism that comes to women giving birth to children at the end of the ability to get pregnant.

There might be some truth in this, but recent work by Sarah Blaffer Hrdy suggests that new borns, with no older siblings, raised in Western households with often only mothers as an integral other, don’t as easily develop theory of mind.

As regards the theory above, perhaps autism that emerges from different causes could be parsed out by differences in digital facility. Perhaps those traumatized exhibit a different effortless use of fingers and limbs than those without an environment that encourages theory of mind.

Hand preference and hand skill were assessed in 20 children with autism, 20 normal controls and 12 children with mental retardation. 90% of the normal controls and 92% of the children with mental retardation showed concordance for hand preference and hand skill (i.e. the preferred hand was also the more skillful), whereas only 50% of the children with autism showed concordance of preference and skill, the remaining 50% preferring to use the hand which was less skillful. Children with autism also showed a lesser degree of handedness and a lesser degree of consistency than the other groups, although this was unrelated to the discordance of skill and asymmetry. A developmental model of handedness is proposed in which the development of handedness as preference is ontogenetically prior to the development of handedness as skill asymmetry, such that in normal children the development of skill asymmetry occurs as a secondary consequence of the establishment of preference. The causal sequence is disrupted in autism, so that although preference is established, it does not subsequently result in concordant skill asymmetry. (McManus, I. C., Murray, B., Doyle, K. & Baron-Cohen, S. (1992). Handedness in childhood autism shows a dissociation of skill and preference. Cortex, 28(3), 373-81.)

There are differences in handedness amoung varying cultures around the world. Asian societies display around 2%. It is not clear how much of this is due to its being discouraged. Some American Aboriginal populations show 12% left handedness (Canadian Northwest populations).

What’s at issue here is the relationship between handedness, maturational delay, and autism. If there are variations among the autistic between those that use a hand that is more adept and those that do not, with more autistics using the left hand than the general population, then perhaps the autistic are more guided by Annett’s right shift theory with their being random handed to such a degree that choosing a less adept hand is not inhibited.

A question would be, among those NW Indian tribes, do they also often choose to emphasize a hand that is less adept?

If the results from these three studies are combined, the overall proportion of left-handers is 13.3 per cent for autistic children and 8.3 per cent for matched controls, not a significant difference.  However, if left- and mixed-handers are summed, then the frequency of non-right-handedness among autistic children is considerably higher than that found in age-matched normally developing children, although it is similar to that found in other children of the same intellectual ability  (Bishop, D. V. M. (1990). Handedness and developmental disorder. London: Mac Keith Press.  p. 111)

There is a close associated between handedness and maturational delay. There is a close association between autism and handedness. There is a close association between maturational delay and autism. There is a close association between a mother’s testosteone levels and her children’s handedness and autism.

Seems pretty clear that a mother’s testosterone levels are closely associated with maturation rate.  There is a whole science devoted to maturation rates as those rates relate to evolution. That science is called heterochrony. Consider that autism is an evolutionary condition.

This paper is concerned with what abnormal handedness in Pervasive Developmental Disorders (PDD) reveals about the presence, lateralization, and severity of cerebral dysfunction in this population. From previous work, it was predicted that left-handedness would be elevated in the sample and that mixed-handedness subjects should be more impaired than those with established hand dominance. A battery of cognitive and motor tests were administered to a group of PDD children with autistic symptoms, and performance was compared for the left-handed, right-handed, and mixed-preference children. It was found that left-handers tended to do better than right-handers on all cognitive measures, while the mixed-preference children tended to be the lowest on all cognitive measures. No differences were found on motor measures. An extension of the Satz (1972) model, assuming early brain damage, was developed to explain the superiority of the left-handed children; an alternative explanation assuming anomalous lateralization patterns in the natural left-handers was also suggested. (Fein, D., Waterhouse, L. Lucci, D., Pennington, B. & Humes, M. (1985). Handedness and cognitive functions in pervasive developmental disorders. Journal of Autism and Developmental Disorders, 15, 323-33.)

Interesting that mixed handedness performs lower than the left or right handedness. Other studies have concluded that many mixed handers excel in sports such as tennis. Perhaps mixed handedness mixes extremely adept with extremely impaired. Of course, it is also interesting that left handers exceed right handers in dexterity.

Exploring this evolutionarily in the context of cerebral laterailization and Annett’s right shift theory that left handers are random handed, the study above might suggest that lefties are our evolutionary forebears (less cerebral lateralization) and mixed handers are those having trouble making the transition to current right handed neurologies. A problem with this is that Annett suggests both left handers and right handers are random handed, trending toward having no gene for handedness. Why would only mixed handers reveal problems?

BACKGROUND: Sex-differences exist in some areas of human social behaviour. In animals, foetal testosterone (fT) plays a central role in organising the brain and in later social behaviour. fT has also been implicated in language development, eye-contact, and spatial ability in humans. METHODS: Fifty-eight children (35 male and 23 female), whose fT was analysed in amniotic fluid, were followed up at age 4. Their mothers completed the Children’s Communication Checklist, a questionnaire assessing language, quality of social relationships and restricted interests. RESULTS: fT was negatively correlated to quality of social relationships, taking sex-differences into account. fT was also positively correlated with restricted interests in boys. CONCLUSIONS: These findings implicate fT in both social development and attentional focus. They may also have implications for understanding the sex ratio in autism. (Knickmeyer, R., Baron-Cohen, S., Raggatt, P. & Taylor K. (2005). Journal of Child Psychology and Psychiatry, and Allied Disciplines, 46(2), 198-210.)

I keep thinking that estrogen may be integral to understanding the timing of maturation in addition to testosterone influencing the rate of maturation. The rate of maturation seems central to the kinds of discoveries above. Click here for an exploration of the possible effects of estrogen.

Empathy involves an understanding of what others are thinking and feeling, and enables us to interact in the social world. According to the Empathizing-Systemizing (E-S) theory, females on average have a stronger drive to empathize than males. This sex difference may in part reflect developmental differences in brain structure and function, which are themselves under the influence of fetal testosterone (fT). Previous studies have found that fT is inversely correlated with social behaviors such as eye contact in infancy, peer relationships in preschoolers, and mentalistic interpretation of animate motion. Male fetuses are exposed to higher levels of testosterone than are female fetuses. The present study investigates empathizing in children, as a function of amniotic measures of fT. One hundred ninety-three mothers of children (100 males, 93 females) aged 6-8 years of age completed children’s versions of the Empathy Quotient (EQ-C), and the children themselves were tested on “Reading the Mind in the Eyes” Task (Eyes-C). All mothers had had amniocentesis during the 2nd trimester of pregnancy. There was a significant negative correlation between fT and scores on both measures. While empathy may be influenced by post-natal experience, these results suggest that pre-natal biology also plays an important role, mediated by androgen effects in the brain. These results also have implications for the causes of disabilities involving empathy, such as autism spectrum conditions, and may explain the increased rate of such conditions among males. (Chapman, E., Baron-Cohen, S., Auyeung, B., Knickmeyer, R., Taylor, K. & Hackett, G. (2006). Fetal testosterone and empathy: Evidence from the empathy quotient (EQ) and the “reading the mind in the eyes” test. Social Neuroscience, 1(2), 135-48.)

Sarah Blaffer Hrdy’s Mothers and Others describes the intensity with which aboriginal hunter gatherer societies teach egalitarian principles that include sharing and thinking of others. Many of these societies are matrilocal with males compelled to travel to find a wife. I’ve hypothesized that our matrifocal hunter gatherer forebears feature high testosterone females and low testosterone males. What if it is necessary the compassion or empathy be a taught experience in societies where women have high testosterone? High testosterone wombs are associated with children exhibiting autism.

What I’m getting at here is perhaps we evolved with societal structures that prevented autism or difficulties developing theory of mind by intensely teaching to think of others. High testosterone women may less reflexively exhibit compassion requiring a social intervention to make it intuitive.