The Utopian- A rEvolutionary Blog

In the halls of academia researchers are often more concerned about protecting their intellectual property than publishing the truth. Blogging offers a way to respect previous research, mine the information glut, and quickly publish the results. This blog is an experiment in gathering, documenting, associating, and presenting important information about human evolution using only a browser, the internet, and copy/paste techniques. These are not "my" words. I am only the editor.

Location: United States

I have a BS degree in Wildlife from O.S.U. but most of my education comes from self study. I don't watch much TV because I don't think subjecting myself to all the materialistic and social propaganda is healthy. You can't view the world clearly if you put blinders on. My conclusions about the literature I cite on this website will be confined to the comments section. Please read those comments if you want to see the insights I have gained from my personal study. An interesting thing happened when I began this experiment. I discovered that bolding the important points of the research I was citing produced a rough summary of the information I could scan quickly, and also provided a easily referenced outline I could use to associate data from different sources using multiple browser windows. This led to a number of personal insights. Learning how to use blogs to data mine effectively can contribute greatly to the spread of global knowledge, and reduce the "information glut" that has accumulated.

Saturday, February 12, 2005

Human eating behaviour in an evolutionary ecological context.

"One hallmark trait of human feeding behaviour, complex control of food availability, emerged with Homo erectus (1.9 x 10(6)-200000 years ago), who carried out this process by either increased meat eating or by cooking, or both. Another key trait of human eating behaviour is the symbolic use of food, which emerged with modern Homo sapiens (100000 years ago to the present) between 25000 and 12000 years ago. From this and subsequent social and economic transformations, including the origins of agriculture, humans have come to use food in increasingly elaborate symbolic ways,"
Light My Fire: Cooking As Key To Modern Human Evolution

"Fire provided the "spark" for modern human evolution, but not because it allowed our ancestors to eat meat. Rather, it was the ability to cook tuberous roots akin to carrots, potatoes and beets that caused hominids to turn a major evolutionary corner about 1.9 million years ago."

"The researchers link the advent of tuber cooking to changes in body size and tooth size that separated Homo erectus from earlier hominids such as australopithecines, of which "Lucy" is the most famous specimen. They said that tuber cooking could also have brought about basic changes in hominid social structure. The key word is cooking, not tubers."

"The process of human evolution had much to do with food and how it was prepared," said Laden. Australopithecines like Lucy had huge teeth suitable for chewing all day long, and males were much bigger than females. But 1.9 million years ago, things changed. Teeth got smaller, and both sexes increased in size. Females increased in size more than males, and so the size gap between the sexes shrank. Homo erectus had arrived, and cooking of tubers made the difference."

"We strongly suspect hominids began using fire about 1.9 million years ago, when Homo erectus appeared," said Laden. "The evidence for fire this early is a bit tenuous, but once word got out about our idea, we were contacted by colleagues working in East Africa who are about to publish very strong evidence for human-controlled fire at a very early date. In any event, fire wouldn't have worked as a 'spark' to evolution if roots hadn't already been in the diet."

"According to Laden and his colleagues, both Lucy and Homo erectus ate tubers, but Lucy ate them raw. Thus, she and her australopithecine relatives had huge teeth and strong jaws. But with the advent of fire, hominids were able to cook tubers, which softened them, making chewing easier, and increased the amount of available nutrients."

"Teeth no longer had to be huge and suitable for constant chewing. Further, cooking allowed hominids to expand their diets. Many tubers are poisonous unless cooked, so cooking opened up new food sources. The use of tubers may have helped australopithecines expand their range from rainforest to savanna, where tubers were numerous. But cooking foods went beyond this, said Laden, and had profound effects on early human size and social behavior."

"On an evolutionary scale, male primates are limited in reproduction by access to females," said Laden, "but females are limited by access to resources." When cooking increased the supply of calories, females were able to grow to a larger size. At the same time, a decrease in the male-female size difference signalled a change in mating systems."

"Highly polygynous mating systems, such as the harem system of gorillas or the promiscuous mating of chimps, are typically associated with males being much larger than females," said Laden. "When male and female mammals are close in size, pair bonding is the rule. So this change about 1.9 million years ago is probably best explained as a change in mating practices."

"This social change is probably more important than, and was caused by, the expansion of the diet, Laden said. Cooking required changes in how food was prepared. Like living chimps, australopithecines would have eaten food on the spot whenever it was found. But cooking meant bringing food to a common site for processing, where other members of the group--including larger and more dominant individuals--could see it."

"We propose that cooking opens the door for theft, so among cooking hominids, there would have been cause to cooperate in new ways," said Laden. Females would have been vulnerable to theft by much larger males. This would have resulted in evolutionary pressure for females to form bonds with males, basing their choice on male willingness to cooperate in defending food stores rather than on male size."

"Laden and his colleagues believe this might have led to an important evolutionary novelty of humans: female sexual attractiveness. Unlike humans, other female primates are sexually attractive only around the time of ovulation, as indicated by obvious physical and behavioral changes, Laden said. But women are generally attractive to males, and this is part of the process by which long-term bonds can form between individuals. This would have lessened the benefit many male mammals gain from direct competition for females in heat."

"We don't know if males or females invented cooking, or who did the cooking, but the kind of 'scramble' competition we see in primates would have made a cooking-based strategy impossible, while pair bonding and formation of a sort of family around a hearth would be a stable, evolutionarily sensible strategy," he said."

"All these changes resulted in humans becoming a species that ate a wider variety of foods than their ancestors, formed more stable pair bonds and cooperated in cooking and defending food stores."


Blogger The Utopian said...

I generally like the conclusions these researchers reached, but I think they are jumping to conclusions about their findings leading to female sexual attractiveness.

While it is true that a lesser degree of sexual dimorphism tends to promote pair bonding, that bonding doesnt necessarily occur between males and females. As Evelyn Reed has shown, it can also mean female-female pair bonding.
Contrary to their statement, female sexual attractiveness is also not a novelty only of humans. Bonobos exhibit female sexual attractiveness too, and can participate in sex year round.

Cooking no doubt opened the door to the possibility of theft, and it probably did promote new types of cooperation, but saying that "it would have resulted in evolutionary pressure for females to form bonds with males" is pushing the truth.

Lets say the females were gathering the roots and bringing them "home" to be cooked for example, and a larger male decided to steal the roots. Why wouldn't the females be just as likely to cooperate to fight off the male? I can think of a number of scenarios that could occur actually. Why couldn't multiple males cooperate to steal the roots from the whole group for instance?

We need to be careful about social bias creeping into our research conclusions. I think its safe to say a number of possibilities could happen in a given case, and the result will most likely be determined partially by the habits already established within the group.

If females were already in control of the group's food for instance, then they would probably remain in control. They may need to guard the roots while they cook em, but they would still maintain control.

If we assume that males were already in control of the group's food however, then most likely the males would try to steal the food. That still doesnt necessarily mean that the females would try to convince another male to help them defend the food however.

I think we need to look for another hypothesis to explain female sexual attractiveness.

1:31 AM  
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9:27 AM  
Anonymous Anonymous said...

If I may ??? I am going to share this information and commentary with my culinary arts and chef apprenticeship students. It WILL assist them in thinking "out of the kitchen". Good stuff! Stay with it, cuz.

1:02 PM  

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