Natural selection on human twinning
Article Abstract:
The lifetime reproductive success of mothers of twins compared with singleton mothers differed significantly between the archipelago of Aland and Aboland, Finland, and mainland areas of Finland in the period 1752 to 1850. Lifetime reproductive success was maximized by having twins on the archipelago. In contrast, the reproductive output of mothers of twins on the mainland was substantially lower than that of control mothers. This research supports the hypothesis that differences in twinning frequencies in human populations that have been quite isolated could be maintained by natural selection.
Publication Name: Nature
Subject: Zoology and wildlife conservation
ISSN: 0028-0836
Year: 1998
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Primary motor cortex is involved in bimanual coordination
Article Abstract:
Certain voluntary movements involve coordination between the limbs. The neuronal mechanisms mediating this coordination have not been extensively studied. The activity of cortical neurons have been studied during tasks performed by monkeys requiring coordination between the two arms. Most primary motor cortex (MI) neurons showed activity specific to bimanual movements. Units in the supplementary motor (SMA) exhibited no more bimanual-related activity than MI units.
Publication Name: Nature
Subject: Zoology and wildlife conservation
ISSN: 0028-0836
Year: 1998
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