By April MacIntyre Dec 20, 2008, 23:43 GMT
Tomorrow, Sunday (12/21/08), the National Geographic Channel will debut "In the Womb: Identical Twins.
Courtesy of National Geographic
From a single cell to blastocyst, embryo and onward to a complex, self-sustaining organism, an infant goes through an incredible transformation before it even takes its first breath. Two infants in utero are even more remarkable, as is the science of genetics that benefits from studying the personalities, proclivities and physical health of the dual womb-mates after their birth.
Nat Geo producers have utilized ground-breaking photography, computer graphics, and 4-D imaging to bring you the first in a series, "In the Womb" reveals this amazing process for humans, and for animals in subsequent episodes.
The footage is fascinating and I recommend it highly for anyone, including children.
While identical twins are as close as nature gets to human cloning, the differences are there, and scientists have discovered that nature and environment do play a role especially in matters of longevity and disease.
"In the Womb: Identical Twins" also explores how genes not only play a role in appearance but also how they affect personalities, sexual preferences and other characteristics. Gender preferences,the gay/straight nature versus nurture question is addressed too. It seems in male twins, (if they are identical) there is a 50% chance both will be gay. First trimester testosterone saturation in male embryo brains is the assumed culprit for whether a boy will fancy girls or his own sex.
Nat Geo compiled interesting facts about twins:
About 95 percent of all multiple births in the United States are twins.
34 out of every 1,000 births in the United States are multiples.
Between 1980 and 1998, the rate of triplets and higher order births in the United States increased by 400 percent. In recent years, this rate has been more stable.
A woman has an estimated one in 64 million chance of conceiving identical quads.
Women reaching the end of their reproductive years are more likely to have a multiple pregnancy.
The window for an egg splitting to form identical twins is very short. If the egg doesn’t split into two separate but identical eggs within the first 14 days after conception, it never will.
The record number of fetuses in a human womb at one time is 15.
It’s estimated that for every 400 sets of fraternal twins, one set is made up of twins who will have different fathers.
At birth, single babies on average weigh more than twins.
Some fetuses spend the first trimester of pregnancy with a companion that later disappears—a phenomenon called the “vanishing twin syndrome.”
Movements such as kicking, pushing, and what looks like kissing are all documented in twins.
Interaction between twins may be beneficial, helping to accelerate their development.
About half of twins are delivered by Cesarean section (or C-section).
Nat Geo producers touch on the parasitic twin syndrome, and reintroduce little Lakshmi Tatma (seen previously in the Girl with Eight Limbs). Born with four arms and four legs, she's joined to her partially formed parasitic twin.
Producers show exactly how doctors rebuilt her pelvis and excised the parasitic twin thus allowing Lakshmi to live a normal life.
Side note: I would have like to seen more about the parasitic twins that are absorbed by the dominant embryo that become Dermoid tumors. Dermoids and Teratomas consist largely of tissues of ectodermal origin such as skin, hair and teeth. They're gnarly, but very interesting to see if you have a strong stomach.
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