20 MAR 2018 by ideonexus

 Human Females Menstruate to Eliminate Unviable Fetuses

From a female perspective, pregnancy is always a huge investment. Even more so if her species has a hemochorial placenta. Once that placenta is in place, she not only loses full control of her own hormones, she also risks hemorrhage when it comes out. So it makes sense that females want to screen embryos very, very carefully. Going through pregnancy with a weak, inviable or even sub-par fetus isn't worth it. That's where the endometrium comes in. You've probably read about how the endometriu...
Folksonomies: human evolution pregnancy
Folksonomies: human evolution pregnancy
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20 MAR 2018 by ideonexus

 Human Pregnancy is Adversarial Between Mother and Fetus

Inside the uterus we have a thick layer of endometrial tissue, which contains only tiny blood vessels. The endometrium seals off our main blood supply from the newly implanted embryo. The growing placenta literally burrows through this layer, rips into arterial walls and re-wires them to channel blood straight to the hungry embryo. It delves deep into the surrounding tissues, razes them and pumps the arteries full of hormones so they expand into the space created. It paralyzes these arteries ...
Folksonomies: human evolution pregnancy
Folksonomies: human evolution pregnancy
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09 AUG 2014 by ideonexus

 The Mother's Womb Tests the Viability of the Fetus

Given the invasive nature of pregnancy, it’s perhaps not surprising that the primate womb has evolved to be wary of committing to it. Mammals whose placentae don’t breach the walls of the womb can simply abort or reabsorb unwanted foetuses at any stage of pregnancy. For primates, any such manoeuvre runs the risk of haemorrhage, as the placenta rips away from the mother’s enlarged and paralysed arterial system. And that, in a sentence, is why miscarriages are so dangerous. It’s also w...
Folksonomies: pregnancy biology
Folksonomies: pregnancy biology
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09 AUG 2014 by ideonexus

 Invasive Blood-Seeking Fetuses in Mammals

In most mammals, the mother’s blood supply remains safely isolated from the foetus. It passes its nutrients to the foetus through a filter, which the mother controls. The mother is a despot: she provides only what she chooses, which makes her largely invulnerable to paternal manipulation during pregnancy. In primates and mice, it’s a different story. Cells from the invading placenta digest their way through the endometrial surface, puncturing the mother’s arteries, swarming inside and ...
Folksonomies: evolution pregnancy
Folksonomies: evolution pregnancy
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18 JAN 2013 by ideonexus

 When Does Human Life Begin

Careful and reproducible observations and measurements in the bbiosciences have similarly forced us to repeatedly refine our traditional ideas about what life itself is and when it begins. Is a human being first a life when it emerges from the birth canal? Does it have any legal rights is as a person before then? Or is it a life at the stage of development where > it is able to survive independently outside of the womb even if it is removed from there early, as can happen naturally with pr...
Folksonomies: science biology life abortion
Folksonomies: science biology life abortion
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Is it at fertilization, implantation, or after birth?