吃肉缩减了人类的哺乳期-凯发k8官网

吃肉缩减了人类的哺乳期
文章来源:未知 文章作者:enread 发布时间:2012-04-23 04:39 字体: [ ] 
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carnivory is behind the 1 success of humankind. when early humans started to eat meat and eventually hunt, their new, higher-quality diet meant that women could wean(使断奶) their children earlier. women could then give birth to more children during their reproductive life, which is a possible contribution to the population gradually spreading over the world. the connection between eating meat and a faster weaning process is shown by a research group from lund university in sweden, which compared close to 70 mammalian species and found clear patterns. learning to hunt was a decisive step in human evolution. hunting 2 communication, planning and the use of tools, all of which demanded a larger brain. at the same time, adding meat to the diet made it possible to develop this larger brain.

"this has been known for a long time. however, no one has 3 shown the strong connection between meat eating and the duration of breast-feeding, which is a crucial piece of the puzzle in this context. eating meat enabled the breast-feeding periods and 4 the time between births, to be shortened. this must have had a crucial impact on human evolution," says elia psouni of lund university.

she is a developmental psychologist and has, together with neurophysiologist martin garwicz (also in lund) and evolutionary geneticist axel janke (currently in frankfurt but previously in lund) published her findings in the journal plos one.

among natural fertility societies, the average duration of breast-feeding is 2 years and 4 months. this is not much in relation to the maximum lifespan of our species, around 120 years. it is even less if compared to our closest relatives: female chimpanzees suckle(给哺乳,养育) their young for 4-5 years, whereas the maximum lifespan for chimpanzees is only 60 years.

many researchers have tried to explain the 5 shorter breast-feeding period of humans based on social and behavioral theories of parenting and family size. but the lund group has now shown that humans are in fact no different than other mammals with respect to the 6 of weaning. if you enter brain development and diet composition into the equation, the time when our young stop suckling fits 7 with the pattern in other mammals.

this is the type of mathematical model that elia psouni and her colleagues have built. they entered data on close to 70 mammalian species of various types into the model -- data on brain size and diet. species for which at least 20 per cent of the energy content of their diet comes from meat were categorised as carnivores. the model shows that the young of all species cease to suckle when their brains have reached a particular stage of development on the path from conception to full brain-size. carnivores, due to their high quality diet, can wean earlier than herbivores and omnivores.



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1 ctqz7m     
adj.进化的;演化的,演变的;[生]进化论的
参考例句:
  • life has its own evolutionary process.生命有其自身的进化过程。
  • these are fascinating questions to be resolved by the evolutionary studies of plants.这些十分吸引人的问题将在研究植物进化过程中得以解决。
2 584daebbe9eef7edd8f9bba973dc3386     
使…成为必要,需要( necessitate的过去式和过去分词 )
参考例句:
  • recent financial scandals have necessitated changes in parliamentary procedures. 最近的金融丑闻使得议会程序必须改革。
  • no man is necessitated to do wrong. 没有人是被迫去作错事的。
3 bkzzzc     
adv.以前,先前(地)
参考例句:
  • the bicycle tyre blew out at a previously damaged point.自行车胎在以前损坏过的地方又爆开了。
  • let me digress for a moment and explain what had happened previously.让我岔开一会儿,解释原先发生了什么。
4 sokwv     
adv.因此,从而
参考例句:
  • i have never been to that city,,ereby i don't know much about it.我从未去过那座城市,因此对它不怎么熟悉。
  • he became a british citizen,thereby gaining the right to vote.他成了英国公民,因而得到了投票权。
5 bkqzs3     
adv.比较...地,相对地
参考例句:
  • the rabbit is a relatively recent introduction in australia.兔子是相对较新引入澳大利亚的物种。
  • the operation was relatively painless.手术相对来说不痛。
6 rguzgc     
n.时间安排,时间选择
参考例句:
  • the timing of the meeting is not convenient.会议的时间安排不合适。
  • the timing of our statement is very opportune.我们发表声明选择的时机很恰当。
7 zlwzub     
adv.恰好,正好,精确地,细致地
参考例句:
  • it's precisely that sort of slick sales-talk that i mistrust.我不相信的正是那种油腔滑调的推销宣传。
  • the man adjusted very precisely.那个人调得很准。
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