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...

 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 ...

 Physiological Decline in the Body When You Stop Exercising

...regular endurance exercise leads to four major consequences: Increased ability of the heart to eject blood increased ability of the blood vessels to send blood to where blood is needed Increased number of capillaries (the vessels that deliver oxygen and ‘food’ to the muscles) increased size and the number of mitochondria (the “power plants” of the cells). All these changes lead to the more efficient use of oxygen, as well as nutrients. [...] Pino considers a person who can run...

 Altruism is a Basic Human Instinct

The cost for my survival must have been hundreds of millions of dollars. All to save one dorky botanist. Why bother? Well, okay. I know the answer to that. Part of it might be what I represent: progress, science, and the interplanetary future we’ve dreamed of for centuries. But really, they did it because every human being has a basic instinct to help each other out. It might not seem that way sometimes, but it’s true. If a hiker gets lost in the mountains, people will coordinate a sear...

 The Absurd Visions from a Post-Hypnotic Suggestion

I hardly heard him for trying to keep track of what was going on in my skull. I knew it was just post-hypnotic suggestion, even remembered the session in Missouri when they'd implanted it, but that didn't make it any less compelling. My mind reeled under the strong pseudo-memories: shaggy hulks that were Taurans (not at all what we now knew they looked like) boarding a colonists' vessel, eating babies while mothers watched in screaming terror (the colonists never took babies; they wouldn't st...