A mouse feels panicky. It freezes; its little nose twitches. Something is in the air, and it doesn’t like the smell of it. Not one… little… bit.
In mice, the scent of predators causes a surge of stress hormones to course through the blood and induces behavioral changes. Quite a lot is known about olfaction in mice—Richard Axel and Linda Buck split the Nobel Prize in 2004 for elucidating the organization of the thousand or so unique odorant receptors expressed by the sensory neurons in those little noses.
But the neural circuits that transmit a threatening scent from the nose to the hypothalamus, where the stress hormones are released, were not known. Until now.
The majority of predators a mouse is worried about are sight based predators, and they are (almost) hard-wired to follow motion (think your cat with a laser pointer red dot). Freezing until you know where the predator is is almost certainly a survival trait. Hard-wired to follow motion, and much more capable of seeing motion. A mouse could be practically invisible against the background — until it moves and then it’s camouflage could be rendered useless.
Works in humans much the same way. At least, I know there have been many, many times where a bird was right in front of me and I didn’t know it, until it moved. This is part of why blinking lights for cycling came about – solid, always on, lights don’t attract attention if they don’t move fast. The blink/strobe makes the movement pattern more erratic, in hopes of making cyclists at night or low light situations more obvious.
The need to find fuel to generate energy is a profound drive within the biology of all living organisms: we all need food to survive. So it’s not surprising that our bodies have such a complex system to control food intake, driven by hormones.
Male aggression is commonly pinned on testosterone, and estrogen is credited with imparting females with maternal instinct – but the true story of the sex hormones, and their roles in male and female behavior, is a lot more subtle. Here’s why estrogen is an important hormone for males and females alike.
…Using model organisms, biologists have learned some surprising things about the relationship between testosterone, estrogen, and sexually dimorphic behaviors, and wholly debunked the facile notion that testosterone drives male behavior, while estrogen drives female behavior.
Baldness is not a sign of virility, aggression or libido. All it means is that the hair follicles in the scalp are more sensitive to testosterone. It says nothing about overall testosterone levels or how that hormone is being used elsewhere in the body.
I knew brothers in high school, both with the same insane metabolism. Their mother would pack unbelievable amounts of food for their lunch. I don’t remember if they were fast at eating it, but they were both around 6 feet tall and struggled to weigh more than 100 lbs.
I’ve lost contact with those two, but I’ve been encountering similar people in later stages of life. Such people are now dealing with high blood pressure in their mid-30’s, among other medical issues. It comes back to how we as a culture see body fat as an indicator of health. It is to a reasonable extent, but it isn’t the entire picture.
Stuffing down a burger and coke may be more harmful for men than women, if the results of a new mouse study apply to humans.
The detrimental impact of junk food seems to be connected to inflammation in the brains of male mice, with the brains of females protected by oestrogen, according to research published today in Cell Reports.