VOA慢速英语2012 SCIENCE IN THE NEWS - Is Eating Like Our Ancestors Good For Us?

 

SCIENCE IN THE NEWS - Is Eating Like Our Ancestors Good For Us?

From VOA Learning English, this is SCIENCE IN THE NEWS in Special English. I’m Christopher Cruise.

And I’m June Simms. Today we tell about evidence that early humans were meat-eaters much earlier than scientists have thought. We also tell about an ancient relative of humans that probably avoided meat. And we report on a diet that some people say copies the diet of our ancient ancestors.

At least one million five hundred thousand years ago, humans ate meat as part of their daily diet. That is big news to archeologists. The evidence was found in fossilized remains¹ of a young child’s skull². The fossils were recovered from the Olduvai Gorge³ in Tanzania.

Manuel Dominguez-Rodrigo of Spain’s Complutense University has been searching for clues about early humans for twenty years. He has been digging at the Olduvai Gorge since two thousand six. He earlier studied fossils found by the famous British archeologist and anthropologist⁴ Mary Leakey.

“There was an increasing amount of evidence that early humans -- pretty much around two million years ago -- were eating meat. And archeologists over the past fifty years have been debating two main questions. One: was meat an important element in the diet of these hominins or was it just a complimentary⁵ element, like you might see in modern chimpanzees, for instance? And question number two is, whether it was important or not, how did they acquire this meat? Did they hunt the animals they were eating? Did they scavenge the animals they were eating?” 

Archeologists learned from digging in Ethiopia that early humans ate meat as early as two-point-six million years ago. But there are so few knife marks on bone fragments that it is unclear how often meat was eaten.

Now, archeologists can confirm that meat was usually a part of the early humans’ diet at least one-and-one-half million years ago. By studying human remains, scientists know that bones can show signs of dietary problems. The skull fragments in Kenya had bone lesions commonly linked with a lack of B vitamins. This meant the child was weak and anemic from not eating enough meat.

“We don’t find these pathologies commonly in populations that live on hunting and gathering⁶, because the diet of hunter/gatherers is actually more beneficial for human metabolism⁷ than the diet of producers. So our surprise was to find that this pathology typical of sedentary populations actually was found in a prehistoric⁸ hunter-gatherer individual that was (at) one point five million years old.”

He also says he knows the findings will not please vegetarians⁹.

“I’m, I’m fully¹⁰ aware of that, yes, (laughs). We find vitamins, we find folic acid, we find vitamins B-12 now everywhere in the cereals that we eat in the mornings and in many other foods that we take because a lot of that has been artificially produced. But in nature, if we were living on whatever we’re able to obtain by living in a Savannah in Africa, B-12 can only be obtained in meat.”

Professor Dominguez-Rodrigo calls meat, “a crucial element in becoming human.”

Anthropologists have been studying fossilized teeth from a creature that lived two million years ago. The fossils were found in South Africa in two thousand eight.

Anthropologists say the teeth came from Australopithecus sediba or A. sediba. It is one of several hominins, or ape-like species, that no longer exist. They are believed to be relatives -- but not direct ancestors -- of homo sapiens, or modern humans.

The small A. sediba walked upright, just like a homo sapien. But it had a face, a small brain and long arms more like a chimpanzee. A study of material found in its fossilized teeth showed the creature ate a very chimp-like diet of bark, twigs¹¹, nuts and berries.

Darryl de Ruiter is an associate professor of anthropology¹² at Texas A&M University. He was part of the team that first dug up and examined the remains. He says anthropologists looked closely at the sticky plaque¹³ still on the creature’s teeth.

“It’s that stuff -- that plaque -- that builds up on your teeth if you don’t brush them regularly. And since these Australopiths did not brush their teeth, we have a fairly good record of preserved plant parts that were stuck in their teeth, that actually told us in very clear terms what they actually, physically¹⁴ put in their mouth and chewed on.”

Professor de Ruiter says documented diets of other Australopiths that lived on grasslands¹⁵ show they had some form of protein or meat in their diets. He says it appears A. sediba is the first hominid to survive almost completely on a forest-based diet. He says this suggests it lived in a more wooded environment than scientists thought.

“...things like nuts and leaves and berries, and even bark and other components¹⁶ of trees, that chimpanzees regularly, or at least occasionally, feed on. But we’ve never documented them before in Australopith.”

Professor de Ruiter says A. sediba may have added protein to its diet by eating insects or meat.

While Australopiths are related to modern humans in some way, discoveries about the creatures’ diet could help clear up that ancestry¹⁷. A report describing the diet of the A. sediba appeared in the journal Nature. 

The World Health Organization says obesity¹⁸ has more than doubled worldwide since nineteen eighty. Some people are saying the best way to get a healthy body is to learn from our ancient ancestors.

In middle-class economies, eating a healthful diet can be a struggle. Processed snack foods, sweets and packaged meals are everywhere. In the United States, another kind of diet is getting some attention. It is called the Paleo diet.

The Paleo diet combines mainly natural foods that its supporters say humans are genetically-adapted to eat. They include meats, seafood¹⁹, vegetables, fruits, nuts, seeds, roots and tubers. Very few processed foods and no grains are permitted. Sugars and starches²⁰ are limited. And people following the diet closely have no milk products.

Robb Wolf is a former research biochemist. He wrote the book “The Paleo Solution -- The Original Human Diet.”

“We evolved as hunter-gatherers over the course of millions of years, and it’s only been the, the past, you know, couple of thousand years, somewhere between two (thousand) and ten thousand years, that we’ve really transitioned to an agrarian²¹ or agriculture-based way of living.”

Paleolithic humans lived more than ten thousand years ago. They hunted meat and gathered fruits and vegetables. Mr. Wolf says eating those foods is healthier than following the diets of modern farming cultures, which include grains.

Forty-two year old Sean Beliveau has struggled with other diets. He says he has found success by following the Paleo diet.

“As we got into it, I lost about fifty pounds (22.6 kilograms) in the first five months or so on the diet, and kind of stabilized²² into a lifestyle that’s pretty easy to manage and maintain.”

Mr. Beliveau says his blood pressure and cholesterol²³ level have dropped, and his health is better.

Robb Wolf says the Paleo diet helps to treat a number of medical conditions, including Type 2 diabetes²⁴ and heart problems. And he says removing grain from the diet may help ease autoimmune diseases like rheumatoid arthritis²⁵. There is, however, no scientific evidence for these claims. 

Mr. Wolf says many autoimmune diseases have been linked to the addition of grains to the human diet. He says many grain seeds are harmful or hard to process.

“They tend to irritate the immune system -- and rightly so, because this is the reproductive part of the plant. If they didn’t have some sort of anti-predation chemical in them, then, you know, they would just get eaten, and they wouldn’t reproduce.”

Deborah Jeffrey is a registered nutritionist and dietitian²⁶. She says wheat, corn and other grains may worsen some conditions, but they do not affect everyone. 

“I don’t see any evidence that would say the majority of the population has problems. I think it’s because grains and processed white-flour products are things that people tend to over-consume and take in excess calories through, so they just come up with these general statements that they should just be entirely²⁷ avoided.”

Yet that could mean people on the Paleo diet do not get enough carbohydrates²⁸, vitamins and fiber²⁹. This worries dietician Pat Compton.

“The keys have always been with what we should be eating, are balance, variety and moderation. And with this, the Paleo diet, you really are not getting that.”

She adds that our Paleolithic ancestors failed to eat grains because they did not understand their effects on health.

Other nutritionists say the Paleo diet can be part of a healthy lifestyle. But they say many people fail to follow the diet for long periods because it is too restrictive.

But Robb Wolf says it is not difficult to replace grains in one’s diet with other foods. He says people can eat yams or other root vegetables.

In recent years, the Paleo diet has become increasingly popular. But supporters of this way of eating say it can help anyone who wants a healthy lifestyle.

1 remains   

n.剩余物，残留物；遗体，遗迹

参考例句：

• He ate the remains of food hungrily.他狼吞虎咽地吃剩余的食物。
• The remains of the meal were fed to the dog.残羹剩饭喂狗了。

2 skull   

n.头骨；颅骨

参考例句：

• The skull bones fuse between the ages of fifteen and twenty-five.头骨在15至25岁之间长合。
• He fell out of the window and cracked his skull.他从窗子摔了出去，跌裂了颅骨。

3 gorge   

n.咽喉，胃，暴食，山峡；v.塞饱，狼吞虎咽地吃

参考例句：

• East of the gorge leveled out.峡谷东面地势变得平坦起来。
• It made my gorge rise to hear the news.这消息令我作呕。

4 anthropologist   

n.人类学家，人类学者

参考例句：

• The lecturer is an anthropologist.这位讲师是人类学家。
• The anthropologist unearthed the skull of an ancient human at the site.人类学家在这个遗址挖掘出那块古人类的颅骨。

5 complimentary   

adj.赠送的，免费的，赞美的，恭维的

参考例句：

• She made some highly complimentary remarks about their school.她对他们的学校给予高度的评价。
• The supermarket operates a complimentary shuttle service.这家超市提供免费购物班车。

6 gathering   

n.集会，聚会，聚集

参考例句：

• He called on Mr. White to speak at the gathering.他请怀特先生在集会上讲话。
• He is on the wing gathering material for his novels.他正忙于为他的小说收集资料。

7 metabolism   

n.新陈代谢

参考例句：

• After years of dieting,Carol's metabolism was completely out of whack.经过数年的节食，卡罗尔的新陈代谢完全紊乱了。
• All living matter undergoes a process of metabolism.生物都有新陈代谢。

8 prehistoric   

adj.（有记载的）历史以前的，史前的，古老的

参考例句：

• They have found prehistoric remains.他们发现了史前遗迹。
• It was rather like an exhibition of prehistoric electronic equipment.这儿倒像是在展览古老的电子设备。

9 vegetarians   

n.吃素的人( vegetarian的名词复数 )；素食者；素食主义者；食草动物

参考例句：

• Vegetarians are no longer dismissed as cranks. 素食者不再被视为有怪癖的人。
• Vegetarians believe that eating meat is bad karma. 素食者认为吃肉食是造恶业。

10 fully   

adv.完全地，全部地，彻底地；充分地

参考例句：

• The doctor asked me to breathe in,then to breathe out fully.医生让我先吸气，然后全部呼出。
• They soon became fully integrated into the local community.他们很快就完全融入了当地人的圈子。

11 twigs   

细枝，嫩枝( twig的名词复数 )

参考例句：

• Some birds build nests of twigs. 一些鸟用树枝筑巢。
• Willow twigs are pliable. 柳条很软。

12 anthropology   

n.人类学

参考例句：

• I believe he has started reading up anthropology.我相信他已开始深入研究人类学。
• Social anthropology is centrally concerned with the diversity of culture.社会人类学主要关于文化多样性。

13 plaque   

n.饰板，匾，(医)血小板

参考例句：

• There is a commemorative plaque to the artist in the village hall.村公所里有一块纪念该艺术家的牌匾。
• Some Latin words were engraved on the plaque. 牌匾上刻着些拉丁文。

14 physically   

adj.物质上，体格上，身体上，按自然规律

参考例句：

• He was out of sorts physically,as well as disordered mentally.他浑身不舒服，心绪也很乱。
• Every time I think about it I feel physically sick.一想起那件事我就感到极恶心。

15 grasslands   

n.草原，牧场( grassland的名词复数 )

参考例句：

• Songs were heard ringing loud and clear over the grasslands. 草原上扬起清亮激越的歌声。 来自《现代汉英综合大词典》
• Grasslands have been broken and planted to wheat. 草原已经开垦出来，种上了小麦。 来自《简明英汉词典》

16 components   

（机器、设备等的）构成要素，零件，成分； 成分( component的名词复数 )； [物理化学]组分； [数学]分量； （混合物的）组成部分

参考例句：

• the components of a machine 机器部件
• Our chemistry teacher often reduces a compound to its components in lab. 在实验室中化学老师常把化合物分解为各种成分。

17 ancestry   

n.祖先，家世

参考例句：

• Their ancestry settled the land in 1856.他们的祖辈1856年在这块土地上定居下来。
• He is an American of French ancestry.他是法国血统的美国人。

18 obesity   

n.肥胖，肥大

参考例句：

• One effect of overeating may be obesity.吃得过多能导致肥胖。
• Sugar and fat can more easily lead to obesity than some other foods.糖和脂肪比其他食物更容易导致肥胖。

19 seafood   

n.海产食品，海味，海鲜

参考例句：

• There's an excellent seafood restaurant near here.离这儿不远有家非常不错的海鲜馆。
• Shrimps are a popular type of seafood.小虾是比较普遍的一种海味。

20 starches   

n.淀粉( starch的名词复数 )；含淀粉的食物；浆粉v.把（衣服、床单等）浆一浆( starch的第三人称单数 )

参考例句：

• You should avoid sugars and starches. 你应避免吃糖和含淀粉的食物。 来自《简明英汉词典》
• Cotton and rayon yarns are most often sized with water-insoluble starches. 棉和人造丝纱多用不溶于水的淀粉上浆。 来自互联网

21 agrarian   

adj.土地的，农村的，农业的

参考例句：

• People are leaving an agrarian way of life to go to the city.人们正在放弃农业生活方式而转向城市。
• This was a feature of agrarian development in Britain.这是大不列颠土地所有制发展的一个特征。

22 stabilized   

v.（使）稳定， （使）稳固( stabilize的过去式和过去分词 )

参考例句：

• The patient's condition stabilized. 患者的病情稳定下来。
• His blood pressure has stabilized. 他的血压已经稳定下来了。 来自《现代英汉综合大词典》

23 cholesterol   

n.（U）胆固醇

参考例句：

• There is cholesterol in the cell of body.人体细胞里有胆固醇。
• They are determining the serum-protein and cholesterol levels.他们正在测定血清蛋白和胆固醇的浓度。

24 diabetes   

n.糖尿病

参考例句：

• In case of diabetes, physicians advise against the use of sugar.对于糖尿病患者，医生告诫他们不要吃糖。
• Diabetes is caused by a fault in the insulin production of the body.糖尿病是由体內胰岛素分泌失调引起的。

25 arthritis   

n.关节炎

参考例句：

• Rheumatoid arthritis has also been linked with the virus.风湿性关节炎也与这种病毒有关。
• He spent three months in the hospital with acute rheumatic arthritis.他患急性风湿性关节炎，在医院住了三个月。

26 dietitian   

n.营养学家

参考例句：

• You can seek the advice of a nutritionist or dietitian.你可以征求营养师或饮食专家的意见。
• I have no doubt she would make a good dietitian.毫无疑问她会成为优秀的营养学家。

27 entirely   

ad.全部地，完整地；完全地，彻底地

参考例句：

• The fire was entirely caused by their neglect of duty. 那场火灾完全是由于他们失职而引起的。
• His life was entirely given up to the educational work. 他的一生统统献给了教育工作。

28 carbohydrates   

n.碳水化合物，糖类( carbohydrate的名词复数 )；淀粉质或糖类食物

参考例句：

• The plant uses the carbohydrates to make cellulose. 植物用碳水化合物制造纤维素。 来自《简明英汉词典》
• All carbohydrates originate from plants. 所有的碳水化合物均来自植物。 来自辞典例句

29 fiber   

n.纤维，纤维质

参考例句：

• The basic structural unit of yarn is the fiber.纤维是纱的基本结构单元。
• The material must be free of fiber clumps.这种材料必须无纤维块。