Human babies require large and steady supplies of glucose to feed the growing brain. In infants in the first year of life, the brain consumes 60% of all calories, so both babies and their mothers require a dependable food supply. Some evidence suggests that hunters contribute less than half the total food budget of most hunter-gatherer societies, and often much less than half, so that foraging grandmothers can contribute substantially to the survival of grandchildren at times when mothers and fathers are unable to gather enough food for all of their children. In general, selection operates most powerfully during times of famine or other privation. So although grandmothers might not be necessary during good times, many grandchildren cannot survive without them during times of famine. Post-reproductive female orcas tend to lead their pods, especially during years of food scarcity. Furthermore, the increased mortality risk of an orca due to losing a grandmother is stronger in years of food scarcityAnalysis of historical data found that the length of a females post-reproductive lifespan was reflected in the reproductive success of her offspring and the survival of her grandchildren. Another study found comparative effects but only in the maternal grandmother—paternal grandmothers had a detrimental effect on infant mortality (probably due to paternity uncertainty). Differing assistance strategies for maternal and paternal grandmothers have also been demonstrated.
Hematidrosis, also called blood sweat, is a very rare condition in which a human sweats blood. The term is from Ancient Greek haîma/haímatos (αἷμα/αἵματος), meaning blood, and hīdrṓs (ἱδρώς), meaning sweat. Signs and symptoms
Blood usually oozes from the forehead, nails, umbilicus, and other skin surfaces. In addition, oozing from mucocutaneous surfaces causing nosebleeds, bloodstained tears, and vicarious menstruation are common. The episodes may be preceded by intense headache and abdominal pain and are usually self-limiting. In some conditions, the secreted fluid is more dilute and appears to be blood-tinged, while others may have darker bright red secretions resembling blood.While the extent of blood loss generally is minimal, hematidrosis also results in the skin becoming extremely tender and fragile. Causes
Hematidrosis is a condition in which capillary blood vessels that feed the sweat glands rupture, causing them to exude blood, occurring under conditions of extreme physical or emotional stress. Severe mental anxiety activates the sympathetic nervous system to invoke the stress- Fight-or-flight response to such a degree as to cause hemorrhage of the vessels supplying the sweat glands. It has been suggested that acute fear and extreme stress can cause hematidrosis. Diagnosis
Investigation such as platelets count, platelet aggregation test, coagulation profile and skin biopsy reveal no abnormalities and direct light microscopy of fluid demonstrates presence of normal red blood cells. Investigations also failed to show any vasculitis or skin appendages (i.e. sweat glands, sebaceous glands and hair follicles) abnormalities.A 2015 case study investigated hematidrosis with a patient who has epilepsy.