主题：【原创】文化与遗传之一，一定不要怯场呵！ -- 矽藻

These flat birthmarks can be deep brown, slate gray, or blue-black in

color. They do sometimes look similar to bruises. The edges are often, but

not always, indistinct. They are most common on the lower back and

buttocks, but are often found on the legs, back, sides, and shoulders. They

vary from the size of a pinhead to six inches or more across. A child may

have one or several.

At least one Mongolian spot is present on over 90% of Native Americans and

people of African descent, over 80% of Asians, over 70% of Hispanics,and

people of African descent, over 80% of Asians, over 70% of Hispanics, and

just under 10% of fair-skinned infants (Clinical Pediatric Dermatology,

1993). Despite the name, Mongolian spots have no known anthropologic

significance, except for being more common in darker-skinned infants.

T

Mongolian spots are nothing more than dense collections of melanocytes, the

skin cells which contain melanin, the normal pigment of the skin. When the

melanocytes are close to the surface, they look deep brown. The deeper they

are in the skin, the more bluish they look. Either way, they are not

related to bruises or any other medical condition. They do not predispose

to skin cancer or any other problem.

Mongolian spots are present at birth, and most of them fade (at least

somewhat) by age two. Most have completely disappeared by age five. If

Mongolian spots remain at puberty, they are likely to be permanent. Fewer

than five percent of children with Mongolian spots still have any by the

time they reach adulthood. Those who do tend to be the ones with multiple,

widespread spots, or with spots in unusual locations.

Another good explanation: http://www.tokyo-med.ac.jp/genet/msp/about.htm

Some examples of "Mongolian

spots": http://www.tokyo-med.ac.jp/genet/msp/examples.htm

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They are probably called "Mongolian spots" just because they were first

noticed in people of Asian descent. Maybe with the new genetic testing

available now, and new testing yet to come, there may be the possibility of

proving them wrong that there is "no known anthropologic significance".

It would still be very interesting to see if one of your sons did

the Y-chromosome testing, and it came up with an East Asian or Native

American haplogroup. :) The Métis have a possibility of being Native

American on their paternal-only or maternal-only lines, either

one. Your children will have your mtDNA, though. May want to look at

whether your husband has a brother or sister who may want to test for their

maternal-only line.