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In humans, the segmentation characteristic observed in the nervous system is of biological and evolutionary significance. [1] Segmentation is a crucial developmental process involved in the patterning and segregation of groups of cells with different features, generating regional properties for such cell groups and organizing them both within ...
Area of the human body surface innervated by each spinal nerve. Even mammals, including humans, show the segmented bilaterian body plan at the level of the nervous system. The spinal cord contains a series of segmental ganglia, each giving rise to motor and sensory nerves that innervate a portion of the body surface and underlying musculature.
The homeobox genes are remarkably conserved between species as diverse as the fruit fly and humans, the basic segmented pattern of the worm or fruit fly being the origin of the segmented spine in humans.
In other taxa, there is some evidence of segmentation in some organs, but this segmentation is not pervasive to the full list of organs mentioned above for arthropods and annelids. One might think of the serially repeated units in many Cycloneuralia, or the segmented body armature of the chitons (which is not accompanied by a segmented coelom). [1]
Ekirch's research into the commonality of biphasic sleep in the preindustrial West has led some to conclude he believes that the human body has a "natural preference for segmented sleep." [10] However, when directly asked if he espoused the idea that biphasic sleep was preferable, he responded: "Not at all. At no time in history have conditions ...
A zoo in eastern China is denying suggestions some of its bears might be people in costumes after photos of the animals standing like humans circulated online. The sun bears from Malaysia are ...
The muscles connected to the ears of a human do not develop enough to have the same mobility allowed to monkeys. Arrows show the vestigial structure called Darwin's tubercle. In the context of human evolution, vestigiality involves those traits occurring in humans that have lost all or most of their original function through evolution. Although ...
The palm has five bones known as metacarpal bones, one to each of the five digits. Human hands contain fourteen digital bones, also called phalanges, or phalanx bones: two in the thumb (the thumb has no middle phalanx) and three in each of the four fingers. These are the distal phalanx, carrying the nail, the middle phalanx, and the proximal ...