The landscape in which early man lived changed rapidly back and forth between closed forest and open grassland about five to six times in a period of 200 years," says Clayton McGill, a graduate student in earth sciences at Penn State University.
A series of rapid changes in East Africa from forest to savannah and back about 2 million years ago may have been the factor responsible for the acceleration of human evolution. This is according to a study by scientists at Penn State and Rutgers Universities.
The landscape in which early man lived changed rapidly back and forth between closed forest and open grassland about five to six times over a period of 200 years," said Clayton McGill, a graduate student in earth sciences at Penn State University. "These changes happened suddenly, with each transition occurring over a period of between a few hundred and a few thousand years.
According to Kathryn Freeman, a professor of earth sciences at Penn State University, the current leading hypothesis suggests that evolutionary changes occurred after one major environmental change in climate. "The perception was that Africa slowly dried up for over three million years," she said. "But our data shows that this was not a continuous progression towards dryness; The environment has changed a lot in all directions and several times.
According to McGill, many anthropologists believe that diversity of experiences can drive cognitive development. "Ancient humans changed from tree-dwellers to grass-dwellers within 10 to 100 generations and their diet had to change accordingly. said. "Changes in food availability, type of food, or amount of food can cause evolutionary mechanisms to act to deal with these changes.
The result was an increase in brain size and cognition, changes in movement and even social changes: how the individual communicates with others in the group. Our data are consistent with these hypotheses.
We show that the environment changed dramatically in a short time, and that this variation coincides with an important period in our human development, when the species Homo appeared for the first time (Homo abilis) and began to use tools."
The two researchers from Penn State and researcher Gail Ashlim, professor of earth and planetary sciences, at Rutgers University examined sediments in a lake in the Oldubai Gorge in northern Tanzania. They removed the organic matter that was washed or blown into the lake and consists of vegetation, bacteria and other organisms that sank two million years ago. They looked at biomarkers – fossilized molecules from ancient organisms – in the waxy coating on plant leaves.
"We looked at leaf waxes because they are made of hard materials that will survive even in these sediments," Freeman said.
The team used gas spectrometry to determine the relative abundance of carbon isotopes in the various leaf waxes. The data allowed them to reconstruct the types of vegetation in the area of the Olduvai Channel in very specific time intervals. The results showed that the environment knew a rapid transition back and forth between a closed forest and an open grassland.
To find out what caused this rapid transition, the researchers used statistical and mathematical models to correlate the changes they saw in the environment with other events at the same time, including changes in the movement of the Earth and changes in sea surface temperatures.
"Earth's orbit around the sun changes slowly over time," Freeman said. "This shift affected the local climate in the Old Bay Channel through changes in the monsoon system in Africa. Slight changes in the amount of sunlight caused disturbances in the strength of the winds and the water supply. The rain patterns that drive the plant patterns have changed due to the fluctuations in the monsoon cycle. We found a correlation between the changes in the environment and the movement of the earth."
The team also found a correlation between changes in the environment and sea surface temperature in the tropics.
"We found two complementary forcing mechanisms: one is through the Earth's orbit, and the other is a change in ocean water temperatures surrounding Africa," Freeman said. The researchers published the results of their study in the journal PNAS of the National Academy of Sciences, along with another study on the same topic that builds on these findings. The second article shows that the amount of precipitation was higher when the environment was forested and full of trees than when the environment was an open savannah.
"The research points to the importance of water in an arid landscape like Africa's," McGill said. "Humans have an intimate relationship with water, because if you have a lack of water, it will usually lead to food insecurity."
"Together, these two documents shed light on human evolution, because we now have an adaptive perspective. We understand, at least to a first approximation, what kinds of conditions were common in this region and we show that changes in food and water would have caused major evolutionary changes."
The National Science Foundation funded the research.
to the notice of the researchers
25 תגובות
Nerds
My reaction to you was harsh because your words had a disparaging tone, so it also seemed to me that the word snarky was aimed at me. Also, you didn't understand that one of the two main claims I had was: brain growth did not come as a result of increasing the amount of protein in the diet of early man. This claim about the protein is a famous claim, even Edward Wilson (who is considered an authority in evolutionary biology) made it. Since this is a famous claim, I tried to refute it by a "detailed calculation" that would explain my argument well. My rebuttal argument is not complicated, but because I was going against a popular opinion I had to explain the argument in detail.
I do not dispute that animal foods are generally more nutritious than plant foods (since the digestive system is more adapted to animal foods). But this matter is not necessary for brain growth, on the other hand, increasing animal food can be a condition for a *general* increase in body mass. It is known that improving the nutrition of animals allows the increase in the general mass of the body both in the short term (non-evolutionary growth) and in the long term (evolutionary growth). I don't dispute that. I also do not dispute that switching to animal foods allows for a general increase in body mass - because animal foods are more nutritious than plant foods. But I had no special interest in this aspect, I tried to be close only to the matter of protein and the connection to the evolutionary growth of the brain.
Regarding the causes of the brain tumor, there are probably many factors and it is difficult to give a complete and accurate assessment of the causes. I have no interest in entering into a discussion about the causes of the brain tumor.
As for obtaining food in increasing quantities by man through hunting, this cannot be done without an increase in intelligence. The example of hyenas is not relevant, hyenas carnivore with the help of their strength (there are cases where they are able to steal prey from big cats such as tigers). Man was always weak and without natural attack tools (like prey teeth, or sprint). In order to be a successful hunter despite his physical limitations, man had to develop intelligence and must develop tools (also open tools in itself requires the development of intelligence).
Language is part of the intelligence and tools that helped develop the hunter. Because language is a tool for passing accurate information between the hunters before and during the hunt. With this I move on to my second main claim: that is, the language developed over a very long period of time (a million years or more).
Many evolutionary biologists discount the complexity of language development, and tend to think that language was invented in the blink of an eye (for example, some say that language was suddenly perfected 75 thousand years ago). In my opinion, language is a much more complicated matter than the development of stone tools and therefore the language developed over a very long time (gradual development).
There are evolutionary biologists who build theories only based on morphological findings, since they do not find morphological findings that indicate modern speech, they claim that there was almost no speech before these morphological findings appeared. Regarding this approach of some evolutionary biologists, as part of my second main argument, I said: for elaborate speech there is no need for a prominent morphological structure, since it is possible to speak complex speech without elaborate morphological tools. For the purpose of my claim "for the purpose of speech... elaborated" - I gave the example of the deaf-mute language (which is carried out effectively despite severe morphological limitations - the lack of ability to speak aloud or hear a voice).
SAFKAN
I read that you are a very hot-tempered person, so I will suggest that you cool down a little
In my response there is no expression of opinion about you and/or your level of intelligence
(You have no reason to be so indignant about the word kashkshan since it appears as a name only)
Because the only criticism is about your opinion (and maybe also about the way you write)
And so it's a shame that you find the need to get down to personal lines
Because you are not the one who tests my wisdom.
Regarding the obsession with protein, I don't understand where it came from
I don't remember such a sentence
And the protein is indeed not the most important part for increasing the volume of the brain.
(As if one could doubt this after the "Torah" or "calculations" you wrote here)
Regarding primate nutrition, a small portion ("meat") is of course relative
And reminding you is a very difficult part to achieve!
In addition to this (and the order of things you presented -in your opinion-)
There is evidence that man began as a scavenger
Not very smart and not very rich (especially enjoys the bone marrow)
But already here there is a need for adaptation from the digestive system
To switch to a hunter that does not require developed intelligence, a method is needed
It was probably persistence and evidence for a long distance relatively to those conditions
(See hunting hyenas - neither elegant nor intelligent but provides glorious meals)
And the most important part for intelligence - what is the selection in its favor?
It is likely that the daily interactions in society are increasing and not necessarily in the hunting method
(although it certainly has an ingredient)
Regarding the volume of the brain, I assume you know that it is not the thing that limits intelligence
(And the volume of the brain does not require a lot of animal protein - did you know?)
Because the connectivity (probably) or other things
So it is not clear to me the great importance you gave to this variable.
And that's without even getting into the "importance of vocal communication" (?!?!)
chatterbox
My long answer to you is pending. Preparation for washing, probably the wait is because I introduced some taboo word, if there is one you deserved it.
chatterbox
The fact that you chose such a nickname does not make you smarter than you are. If you didn't understand what I wrote at length, you are probably not smart.
The fact that you did not understand my calculations about the fact that a person only needs a little protein for the purpose of enlarging the brain indicates that perhaps you are difficult to understand. So you try to throw your difficulties in understanding the calculation on me. Read again, if you have substantive objections to my claims (regarding the lack of need for animal protein in order to enlarge the brain) - raise the objections in a matter-of-fact manner (instead of throwing out words like "babble", words like "babble" are noisy arguments empty of content).
About the ancient man. Its origin is from the primates, all of whom, except man, are distinctly vegetarian, their animal food is a *small part* of their diet. In general: the primates extract almost all the protein from the plant. Therefore, the ancient man did not have a critical problem in obtaining protein from the plant for the purpose of enlarging the brain. The adaptation of the digestive system for a heavy reliance on animal protein is a *very late* development of the ancient man, when he was intelligent enough to hunt large animals and produce a lot of meaty food from the animals. But, for the primitive man to be intelligent his brain had to grow *first*.
In other words, the order of things is reversed (in general):
1) First the brain grows in a state of scarcity of animal food,
2) After the brain grew, the skills (intelligence) for hunting large animals were created,
3) After hunting became the norm - the digestive system of the ancient man accustomed itself to increased consumption of animal food (including protein consumption).
and again Despite your "wisdom" you did not understand the main issue I brought up, the issue is the "protein economy" (not fat, not carbohydrates, not trace foods like iron). The respect of iron fat and all in their place is assumed, but this is not relevant to my claim about the protein economy: a claim was made that "the brain developed only after the meat provided it with protein", on the other hand, I claim that there is no need for animal protein in order to enlarge the brain.
No one disputes that animal food is more nutritious than plant food, but in the early stages of primitive man, animal food was only a small part of the human diet. This is certainly the case with the Homo Bilis whose stone tools (the illusory culture) do not include hunting tools (as far as I know). It is possible that only the erectus began to engage in intensive hunting; But pay attention - probably Eractus already had a big brain (*before* he engaged in intensive hunting).
So that you understand what my main argument is and do not deviate in other directions, I will repeat my argument again 3 times: the protein economy, the protein economy, the protein economy.
That's enough for now. I have a feeling you'll have trouble following a long argument again.
SAFKAN
Meat has a lot of fat - energy - marrow
(without many details and irrelevant "calculations")
And by the way, as you probably know, animal protein is fundamentally different from plant protein
(And so are the accompanying trace elements)
And it's just because you wrote a lot without saying anything,
In relation to the other opinions about the beginning of the language and software hardware and in general about the majority of them I really do not agree
But since they are just opinions and thrown from the hip, I will not comment on that.
skeptic,
Apart from the nutritional analysis, which I am not involved in and cannot say anything about, it seems to me that we are a joint force against... Regarding the development of the brain, the main thing I already said above, I repeat it, like other organs, the brain developed due to selection pressure on its function, that is, on data processing
Yair
Oops...I'm the one who wrote the long comment above (forgot to put in my nick).
Yair
Also in my opinion, language skills developed over a long period of time (at least a million years), it is complete nonsense to say that a language developed only about 75 thousand years ago. The language developed gradually over a very long time, my guess is that the language developed for at least a million years and maybe even 3 million years. The emphasis here is on the word "graduality", in each period of time a language structure was enriched while a slight inclusion.
Biologists think of language too much in terms of hardware while language is a distinct software product (since it requires a cognitive perception of reality, especially the ability to think about concepts in abstract terms, to quantify them, to describe the synchronization of events, to describe the structure of complex objectives). The vocal instruments are not so important for the purpose of language, even with simple vocal instruments it is possible to convey very complex linguistic messages; Note, deaf-mutes are able to have a rich conversation with each other when their vocal instruments are very limited.
In my estimation, the language developed in parallel with the development of the art of making tools since making tools requires strong cognitive skills that get stronger as the tools are perfected. Also, apparently, the language developed simultaneously with the development of group hunting methods (as opposed to individual hunting methods). In group hunting, it is extremely important to be able to quickly convey detailed information by vocal means, because the hunters may be at a considerable distance from each other, the hunters must act quickly so that the hunter does not slip away. Too primitive language messages can fail the hunt.
I also think that the claim that without nutrition the brain cannot develop is not true. Below is the detail of the argument.
Meat provides mainly proteins, not energy, the energy is provided mainly from carbohydrates. Homo sapiens emit excess protein through the kidneys instead of using it for energy, only in a state of hunger is the protein used to provide energy, normally the carbohydrates are provided by the plant food. The mass of a brain is a very small part of the mass of the body, 2 percent maximum in the Spines and a smaller percentage in most of the predecessors of the Spines. Therefore, the protein addition to the brain due to a meat diet is completely negligible (the brain can receive more than enough protein from the protein pool received by the primitive man even before the Abilis period, at that time most of the protein was from plants and the minority was from meat, as in most apes today). In addition to what I said, the role of the liver is to recycle substances in the body, among other things the liver recycles proteins (this is why the daily consumption of proteins is so low). Iron is also intensively recycled in the liver, therefore the amounts of iron consumed on average daily are only a few grams, iron can also be supplied from plants (today we can get it from plants such as tomatoes, peppers, etc.), again, the brain needs
Iron mainly for thinking processes, but the consumption of iron by the whole body is several times greater than that of the brain, which means that increased brain activity does not create a dramatic lack of iron compared to animals with reduced brains (small-brained primates consume iron of mainly plant origin). It is true that eating meat increases the availability of iron, but it is a fact that the small-brained primates were satisfied with small portions of meat. A note regarding the consumption of iron: Iron is mainly consumed by the action of the blood, since iron is the mineral in the red blood cells that enables oxidation-reduction action
We will return to the protein economy (the protein economy = nutrition and waste of protein in the body). Note, even today at the height of the brain's temptation, the spines can get along well with a supply of 80 grams of protein per day, the brain probably consumes a maximum of a tenth of that, i.e. a maximum of 8 grams of protein per day. Therefore, prioritizing the brain (for the purpose of its evolutionary growth) can easily be taken from the protein budget that is required for the rest of the body; Note, even in the vegetarian phase of the ancient man, a lot of protein was required for the rest of the body, especially this was the situation when the mass of the brain was 4 times smaller than today relative to the mass of the rest of the body. I hope you understood this argument, if necessary and if I have time I will elaborate more (the argument I made here is clear enough even without further detail, so I will not repeat the detail if I don't have time).
I will point out right now that the calculations are more complicated than what I mentioned because at the same time as the relative increase of the brain in the primitive man there was usually also a general increase in the mass of the whole body, I don't have time to go into more complicated calculations, I hope you can manage without them, the general idea doesn't change much (although the calculations change as soon as you bring also taking into account changes in body mass as a whole).
As I mentioned in my first response above, there are many mistakes in the article (perhaps the mistakes are mostly those of the journalists who reviewed the article, not all of them are mistakes of the researchers themselves, but I suspect that the researchers also made mistakes). Basically, I do not back down from what I stated in my first response regarding the errors in the article as drafted on this site. Assaf's attempt to argue with me is a failed attempt, I don't have time to argue with him. According to my impression that I know much better than him the evolution of man as well as the geographical and climatic physical conditions that accompanied man. I'm busy with other things, so I don't have the time or desire to argue with him.
Sorry if there were typos or sloppy wording here and there. There is currently no time to check this. If I find time, maybe I will at least repeat my response in a more precise and clear wording.
Machel
Where did you come to the conclusion from my words to avoid dealing with big questions, what I say is that man cannot develop without being influential or without being influenced. Therefore, the attempt to present its development as an isolated process that is not affected by the environment and the creatures living within it is a mistake.
Machel,
Maybe we can agree on the heat. But the structure of the hand and foot have nothing to do with climatic changes, and there is no justification for various claims that the brain developed as a result of nutrition or because of climatic changes, and not for the same reasons that organs develop, that is, due to a choice regarding their function, for which the brain is nothing more than data processing. The main data processing that pressed the brain was the development of voice communication and language, throughout the course of evolution that we are in the current phase. The assumptions that the language revolution is late are nothing more than an unfounded hypothesis. The fact that the brain of the bilis is more than 50% larger than the brain of a chimpanzee and more than twice as erect as a chimpanzee indicates an early development of vocal communication and language, as well as anatomical data, and regardless of climatic changes.
Regarding Assaf's comment in an earlier response that elephants today are younger than humans, it is not true, humans are also somewhat younger than the Cro-Manion, and different from the Spines of 160000 years ago, but as long as it is the same species, these are trivial changes, such as the color of the skin in humans, or the sizes of dogs.
to Ernest,
Good advice for a scientist - the statement "the world is very complex..." must not be an excuse for not saying anything or for avoiding dealing with big questions.
to Ernest,
I mean, do you think the world is too complicated and it's not worth doing science at all?
In general, there is no doubt that it is difficult to differentiate, identify and isolate the processes that lead to a certain evolutionary result. But if there is a strong selection pressure on the organism, it is very possible that it will affect in a very multidisciplinary way and we can tie the ends.
We may have switched to 2 because the bacteria in the stomach wanted us to screw them up at greater distances, or because the parasites wanted us to be eaten by lions so they could infect them.
But once evolution is happening very fast and in many areas at the same time, there may be some selection pressure that can be isolated from the others.
Machel
The human body contains a huge amount of productions living in it that take an active part, it seems to me, in every process that takes place in the body. including changes in the genome. The amount of bacteria in our body is 10 times greater than the number of cells we have built, and there is a huge number of viruses and others in our body, to that we will add the external effects if it is from the climate from food and other productions, we will actually get a very complex organism.
So how can we know if a certain change was caused from the inside, let's say by a virus that acts in or on a certain gene or is it from an external influence or is it both this and that, or is it a random mutation...
Liir,
As I mentioned, once a stone starts rolling, it won't necessarily end up where you pushed it. In addition, as far as I know the voice changes happened relatively late. In fact, it is speculated that the language revolution happened in full force only a few tens-hundreds of thousands of years ago.
I'm glad you agree that a very good adaptation to heat is what we would expect in the case of climate change. All that remains is for you to agree that humans are also very adapted to heat, as I described in my previous response, and then we will completely agree.
Which animals, for example, are more resistant to heat than humans?
Machel
If it is true that man is more resistant to heat than other animals - there are animals in Africa and other hot places that spend all day in the sun grazing - this is exactly the type of change we would expect due to climatic selection pressure. But the other changes I presented in the previous response have nothing to do with climate. On the other hand, the chimpanzee, the gorilla, the baboon, which represent evolutionary branching points, certainly remained similar to their predecessors, even if we are obliged to assume that evolution did not bypass them. And the same for animals of all other species. There is no reason to assume that the huge change in vocal communication, the development of language was related to climate.
Liir,
First, there is no doubt that the evolution that man went through was very fast.
On the other hand, you still haven't substantiated your argument that other animals did not undergo significant changes during this period (remained similar to their ancestors? trivial evolution? what? what is your background in paleontology?)
There is no doubt about something else - every creature responds to changes in environmental conditions according to a certain genetic potential. This is similar to stones - there are stones that will not move too much if pushed, but there are stones that are just standing on the face of an abyss, and the push will move them very far.
That is, it is very possible that man's ancestors were on the brink of an evolutionary "abyss", and something, external or internal, pushed them to it.
But was that something climate change and how strong was the push?
As far as I know, the current research strongly emphasizes the impact of climate change. Did you know that humans are one of the most heat resistant animals in the world (not to dryness, to heat). We have the ability to sweat a liter and a half per hour (!), and in particular our ability to cool the head and neck area is amazing. Setting it to 2 also helps to reduce the radiation flux on the whole body. Also the matter of the loss of hair (not fur, by the way) and the change of skin color from light (as in monkeys) to dark fits into this overall picture in a great way (what is your explanation for the matter? What is the matter of the species?). Standing upright fits into this matter in another aspect - food in the savannah is very spotty, and going on 2 has a clear advantage in finding it and reaching it (even at the height of the heat, when the other animals are not active).
There seems to be a very nice overall picture here.
Of course, external changes are also in interaction with "internal" changes - the transition to walking on 2 creates difficulty in childbirth and makes babies very dependent on their parents. From this, two parents are required for parental care, and a monogamous system is created in which there is also less marital dimorphism (as a rule).
So why do you claim with such fervor that climate change is irrelevant?
To Machel and Assaf
The evolution of man was dramatic and many changes, in all the organs of the body. The evolution of elephants and crocodiles was trivial, and today's animals are not fundamentally different from their predecessors, man is different from the chimpanzee, the gorilla and the baboon who lived in the same areas and made a living most of the time from the same food sources. The main selective pressures on human evolution were in the internal system of the hominids and not in the processes of nature. Developments such as the structure of the hand, the structure of the brain, its size, language ability and general cognition, the structure of the foot, the difference in the shape of male and female, all these have nothing to do with climatic processes. In fact even the loss of fur is probably more related to sexual processes than climate.
to the skeptic
- The study refers in detail to the appearance of the human species (homo), which is estimated to be about three million years old
And that the first of the genus was Homo habilis (the skilled man), hence all your "scholarly" attitude
An "ancestor" is out of place,
- The Milankiewicz cycle is a well-known and measured phenomenon (not a theory) and therefore not hidden,
- Changes in land cover in Africa (as in the whole world) are affected by the climate
which is (also) affected by the Milkwitz cycle.
- The climate changes in East Africa in the last millions and hundreds of thousands of years are known
When the (recent) retreat of forests began with the onset of the ice age before
About three million years, a time that corresponds to the appearance of the first human (gay) of his kind,
(The "Ice Age" house must be distinguished from the Ice Age in which we have been for about 35 million years)
- The study was conducted in the Old Dubai channel since that is where the findings that are associated were discovered
For the first and second types of man (homo) in the homo lineage -
The skilled man (Homo habilis) and the upright man (Homo erectus).
- Since the African depression is considered to be the area where human species developed
And since the Olduvai Gorge is one of the most important sites for the study of paleontology
And since it is located in the African depression, it is clear that it was chosen as a base for research,
- in the paragraph that begins with "It's hard to believe ……." You relate to Roy's (joking) reaction
Because research is not based on faith but on facts.
The changes also caused a rapid evolution in faith in God 🙂
Not sure everything said here is true. Below is a breakdown.
The ancestor of humans is Ardipithecus ramidus (or similar Ardipithecus) and in short his name is Ardi. Hardy was a creature that lived approximately 4.3 million years ago, most of the time Hardy walked on two legs in a completely upright walk, in a minority of the time he climbed trees with the help of the contralateral toe that he had on his foot (the ancestors of humans since 3.3 million years ago do not have a contralateral toe on the foot and therefore they could no longer climb quickly on trees). Therefore, the article's claim that 3 million years ago human ancestors climbed trees is not true.
about the weather It is clearly known that the period of the last 1 million years was a period of extreme fluctuations in the weather (4 glacial periods, 4 glacial periods, when at the same time but not exactly at the same time there were periods of heavy rains in most of Africa that alternated with periods of dryness. There is a known hypothesis that these fluctuations are related to cyclical perturbations of the Earth's axis of rotation (this is the "Milkewitz theory" if I am not mistaken in the name). However, a careful examination of the Milkewitz theory proved that this theory is not reliable (not sufficiently reliable). I have a feeling that in this article Milkewitz was recruited again, so We need to re-examine why we claimed that Milkewitz's theory is not reliable.
Regarding the measurements made in the study. It is implied that all the measurements were made in a limited area (Oldubi area), but it is impossible to draw any far-reaching conclusion from measurements in a limited area (since there may be reasons why climate conditions in a limited area change radically while in most of the nearby areas there is no radical change.
In addition. We know that Africa has always had a tropical forest that sometimes contracted and sometimes expanded. It is hard to believe that the ancestors of humans could not stick to the edges of a shrinking-expanding forest and thus maintain their survival without undergoing any biological change.
Nature is a complex system that is all dependent and connected together. Therefore, it is not possible for one of the components of that system to change by itself without any connection to the others.
Lair
Changes are also seen in other species:
The species of elephants that today live in Africa and Asia are about 40000 years old...younger than humans,
This is also the case with a number of species of monkeys, birds, reptiles and insects.
Changes are also seen in crocodiles, but they are small since for those who live in water
The climate conditions are much more constant compared to the continental conditions
Yair,
An interesting claim. The zero question in this case: why and on what basis do you say that there was no similar acceleration in other stocks?
The claim that climate change has accelerated human evolution is false. We should have seen an acceleration of similar changes in the other animals, monkeys, elephants, crocodiles, it didn't happen. Human evolution did not depend on the climate differently from the other animals