There are endless arguments for why people drink, the simplest being that alcohol is tasty and it makes us feel good.

But those reasons do not address the ultimate explanation for why our brains evolved to like alcohol in the first place, at least according to Robert Dudley, a professor of biology at the University of California, Berkeley, and author of "The Drunken Monkey."

Dudley's drunken monkey hypothesis is the first attempt to place alcoholism in an evolutionary context. In a 2004 paper, he argued that modern patterns of alcohol consumption and abuse have a biological basis that can be traced to our fruit-eating primate ancestors.

Hard-Wired For BoozeSugars in fruits, grains, and nectar are naturally turned to ethanol by yeasts during a process known as fermentation.

The earliest archaeological evidence suggests, based on chemical residues from pottery jars, that humans did not start fermenting honey, rice, and fruit to produce alcoholic beverages until 9,000 years ago.

But these fermented beverages were probably not our first exposure to alcohol, according to Dudley. Our preexisting taste for booze likely developed tens of millions of years ago in our primate ancestors, who survived mostly on fruits.

As fruit ripens, more alcohol is created by the yeasts. When a fruit starts to seriously rot, it can contain up to 8% ethanol, although most ripe fruit contains less than 1%.

Dudley's theory suggests that the alcohol concentration of ripe fruit would have served a purpose for both the fruit-bearing plant and the primate. In tropical forests, fruit can be hard to track down. However, the scent of alcohol from ripe fruits travels long distances, and may have helped primates to find their next meal.

Being attracted to the scent of ethanol from ripe fruits would have been evolutionarily adaptive, enabling the primates to find fruit easier. It was also helpful to the plants, because the primates helped to disperse the seeds in the fruit.

But the gains of eating these alcoholic fruits doesn't end there. Once digested, the theory goes, the alcohol would have stimulated feeding, encouraging the primates to "gobble up the food before anyone else got to it." Humans know this feeling today as the aperitif effect, which you may have experienced if you've ever had a cocktail before a meal and found yourself hungry. Or craved cheese fries after a night out.

Modern Problems Primates probably weren't getting wasted, because fruits house only tiny concentrations of alcohol compared to today's drinks. In one study, Dudley found that the pulp of ripe palm fruits contained ethanol concentrations of 0.9% on average. Most beers have an alcohol strength of 4% and wine usually 14%.

This could explain why a little bit of alcohol can be healthy, he said. The problem today is that humans aren't drinking alcohol in small amounts. Much like the story of sugar — which in ancient times was limited — alcohol is not only plentiful but, thanks to distillation, available in much higher concentrations than found in fruit.

Our bodies have preserved the biological urge to drink from when alcohol sources were few and far between, even though we live in an age where the supply is unlimited.


Read more: http://www.businessinsider.com/why-we-evolved-to-drink-2014-4#ixzz3Gq9Ia6IH

Milk straight from the source contains a variation of vitamins, minerals, fats, sugars, and other factors that promote optimal growth, development, and behavior in babies. Not only does the nutrient content of the milk change over time as the baby grows, but the milk’s composition will actually differ based on the gender of the child. 

In a variety of mammals, including humans, gender also plays an important part in milk composition. Males, who tend to be more muscular, require additional fat and protein. While the fat content in the milk females drink isn’t as high, they tend to consume more milk per meal and will nurse longer. A 2012 study led by Masako Fujita from Michigan State University published in the American Journal of Physical Anthropology showed that human mothers produce milk with 2.8% fat for sons and 1.74% for daughters. In extremely impoverished locations where infant mortality is high, the fat content is higher for girls.

A new study has shown that these differences may very well begin during fetal development. The study was led by evolutionary biologist Katie Hinde from Harvard University and was published in PLOS One. She presented her results this past Saturday at the AAAS 2014 Annual Meeting. The differences appear to begin during fetal development, according to Hinde’s study. Hinde analyzed 2.39 million lactation records from 1.49 million dairy cows and determined that those who had birthed females produced an average of about 445 kg (980 lbs) more milk than those who birthed males, over a two year lactation span. Even if the mother and calf were separated shortly after birth, the volume differences persisted. For cows, however, gender does not impact nutrient content.

For some animals, such as rhesus macaques, social status within the group is passed down from generation to generation. Previous research from Hinde has found that young female rhesus macaques get higher levels of calcium than their brothers, giving them stronger bones and potentially allowing them to reach sexual maturity more quickly. Because females cannot reproduce throughout their entire lives, starting early is an advantage. However, the males receive more cortisol, which helps to regulate metabolism and temperament, allowing them to grow up strong and sire more offspring.

Breast milk is hardly the static, homogenous liquid we are most familiar with from the store. Though the ability to nurse our young is one of the defining features that makes mammals distinct from every other class of animal, there is still an incredible amount about it that we are just discovering. Learning more about how the breast milk is formulated inside the mother’s body will allow us to better understand the ever-changing nutritional needs of babies and could even allow commercial formulas to be reconfigured to better nourish infants when breastfeeding is not an option.