Human evolution theory utilizing concepts of neoteny & female sexual selection
An etiology of neuropsychological disorders such as autism and dyslexia, and the origin of left handedness.
This page contains a collection of excerpts from sources used to support Shift Theory, an alternative theory of human evolution. Click here for an introduction to this new and unique theory of evolution.
"The rate of monozygotic twinning is very much the same throughout the world: about 3 twin births per 1000. The dizygotic twinning rate, however, varies considerably. Thus, some older data showed that in Japan there was approximately 1 dizygotic twin birth out of 165, whereas in the northern countries of Ireland and Scotland the rate was about three times as high. The rates in northern Europe are generally of this order, and those in southern Europe are lower (Bulmer 1970). The highest twinning rates so far observed occur in West Africa, particularly among the Yoruba, especially in the vicinity of Ibaden, where the rate is about 1 in 18 births. In young Yoruba women of high parity the rate of twinning may be nearly 1 in 10 births. It is no surprise that twin dolls are a characteristic feature of Yoruba art. In the United States, Blacks (most of West African descent) have higher twinning rates, and Orientals have lower twinning rates than Caucasians (Bulmer 1970).
"There is also a high rate of neural tube defects in many populations in which dizygotic twinning is common, as it is in Ireland and Scotland. In China, where the rate of dizygotic twinning is very low, neural tube defects occur about one-tenth as frequently as in Ireland (Ghosh et al. 1981). It is very possible that the rate of twin conceptions is higher than is generally appreciated, since in some cases one fetus may die and be reaborbed. The rate of twinning has been falling in recent years in Europe, as has the rate of neural tube defects, data for which no satisfactory explanation has yet been found." (Geschwind & Galaburda 1987: 140-41, Cerebral Lateralization)
"As I explained earlier, the northern dairying people lived in a mist-shrouded environment and had to bundle up against the cold most of the year. They were without access to vitamin D in fish and sea mammals, and lacked green leafy vegetables as an alternative source of calcium. Under these conditions, individuals who were genetically capable of digesting large quantities of unfermented milk were better able to maintain normal bone growth and avoid crippling bone diseases such as rickets and osteomalacia, and therefore enjoyed higher rates of reproductive success than individuals who obtained their calcium through fermented milk, yogurt, or cheese. Within 4,000 or 5,000 years, the gene that controls for lactose production in adulthood spread to over 90 percent of the individuals in northern European dairying populations." (Harris, Marvin (1989) Our Kind. Harper Perennial: New York p. 167)