"What ape did you spring from ?"
Not surprisingly you missed the point of the joke. I will speak more slowly for you. You see, many of us "sprang" far from our heritage in terms of the intellectual and moral gap between ape-like ancestors of our distant past and us...and many (such as some on this thread) show very little gap in those attributes. I.E.--not much spring.
"The evidence for human evolution is overwhelming. This includes thousands of fossils, which show the progressive straightening of the spine, the increase in brain volume, and change in facial features. Humans inherited their tail bone, a remnant of what was once a human tail, from primate ancestors. All animals have a tail at one point in their development; in humans, it is present for a period of 4 weeks, during stages 14 to 22 of human embryogenesis. [2] Humans have a non-functional third eyelid, the plica semilunaris. Humans also have external ear muscles, [3] which animals use to swivel and manipulate their ears (independently of their head) to focus their hearing on particular sounds. Humans still have remnants of such muscles, but they are now feeble and now are capable only of slightly wiggling the ear. [4] DNA comparisons also show that humans share approximately 99% of their DNA with their closest cousin, the chimpanzee (i.e., there is only a 1% difference in the two DNA mappings). Evidence also includes ancestral DNA evidence (" junk DNA") that humans share with earlier ancestors. For example, humans have structures in their genetic make-up that were once used to produce enzymes ( L-gulonolactone oxidase) to process vitamin C; many other animals have this functioning DNA, but at some point in human evolution a mutation disabled the gene, leaving behind its remnants as junk DNA. This particular junk DNA indicates a common ancestry with other species. [5] [6]
The plantaris muscle also serves as evidence of evolution. The plantaris muscle is used by animals in gripping and manipulating objects with their feet, for example apes, who can use their feet as well as their hands for gripping. Humans have corresponding muscles, but it is now so underdeveloped that it is often taken out by doctors when they need tissue for reconstruction in other parts of the body. The muscle is so unimportant to the human body that 9% of humans are now born without it. [7] Other evidence includes Jacobson's organ, which is a part of animal anatomy, and which could figure in the sexual prehistory of humans. This organ, located in the nasal passage, detects pheromones (the chemical that triggers sexual desire, alarm, or information about food trails). This organ allows some animals to track others for sex and to warn of potential dangers. Humans are born with the Jacobson’s organ, but in early development its abilities dwindle to a point that it is useless. [8] In some cases, structures once identified as vestigial simply had an unrecognized function. [9] Wisdom teeth serve as evidence of evolution; human ancestors ate a lot of plants, and they needed to eat them quickly enough that they could eat a sufficient amount in one day to get the necessary nutrition. For this reason they had an extra set of molars to make the larger mouth more productive. This was particularly essential as the body lacked the ability to sufficiently digest cellulose. As evolution made its selections, human dietary patterns changed, the jaw became smaller, and the third molar was not as necessary. [10]
The term "human" in the context of human evolution refers to the genus Homo, but studies of human evolution usually include other hominids, such as the Australopithecines, from which the genus Homo diverged some 2.3-2.4 million years ago in Africa. [11] [12] Scientists have estimated that humans branched off from their common ancestor with chimpanzees about 5–7 million years ago. Several species and subspecies of Homo evolved and are now extinct, introgressed or extant. Examples include Homo erectus (which inhabited Asia, Africa, and Europe) and Neanderthals (either Homo neanderthalensis or Homo sapiens neanderthalensis) (which inhabited Europe and Asia). Archaic Homo sapiens, the forerunner of anatomically modern humans, evolved between 400,000 and 250,000 years ago."
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