Diskusi tentang Perjalanan Kehidupan

[Swan]

Swan,
perkembangan genetik berubah seiring dari kebutuhan spesies, dan kompetisi diantara spesies itu untuk survive,

Contoh, manusia yg sehat dengan mempunyai kebiasaan olah raga, akan mempunyai tubuh yg baik dan akan lebih mudah mendapat pasangan dan bereproduksi..

Adaptasi manusia memang sangat berhubungan dengan kemampuan dan kapasitas otak, sehingga "perbaikan" yg terbanyak dari genetik manusia ada di daerah ini..

tapi seperti yg sebut didepan, masalah enzyme penghancur lemak, kulit akan juga berevolusi, atau manusia "ikut campur" menginisiasi evolusinya sendiri..

Mas bimbim, bukankah seharusnya evolusi itu menuju kesesuatu yang lebih baik? bagaimana pun kita berolah raga, hanya satu banding sejuta dari kita yang bisa mencapai umur diatas 90 tahun. Tapi coba dibandingkan dengan umur manusia jaman dahulu, mereka memilik rata2 umur kehidupan yang lebih lama. Dan lagi, besar kecilnya otak juga nggak memepengaruhi kepandaian seseorang secara general. Orang jepang memiliki otak yang lebih kecil (kapasitasnya) daripada orang bangsa arya, namun banyak juga kahn orang jepang yang menjadi pesaing bangsa arya (orang2 eropa) dalam hal kepandaian, malah orang jepang lebih eksplosif dalam hal teknologi dan sains.

[bimbim]

Mas bimbim, bukankah seharusnya evolusi itu menuju kesesuatu yang lebih baik? bagaimana pun kita berolah raga, hanya satu banding sejuta dari kita yang bisa mencapai umur diatas 90 tahun. Tapi coba dibandingkan dengan umur manusia jaman dahulu, mereka memilik rata2 umur kehidupan yang lebih lama. Dan lagi, besar kecilnya otak juga nggak memepengaruhi kepandaian seseorang secara general. Orang jepang memiliki otak yang lebih kecil (kapasitasnya) daripada orang bangsa arya, namun banyak juga kahn orang jepang yang menjadi pesaing bangsa arya (orang2 eropa) dalam hal kepandaian, malah orang jepang lebih eksplosif dalam hal teknologi dan sains.

Swan,

rata-rata hidup manusia yg menurutmu lebih panjang dapat data darimana ya?

statement mu diatas mau menjelaskan apa sih?
rasanya saya nggak perlu menjelaskan apa2 dari kata-katamu diatas.

[Swan]

Swan,

rata-rata hidup manusia yg menurutmu lebih panjang dapat data darimana ya?

statement mu diatas mau menjelaskan apa sih?
rasanya saya nggak perlu menjelaskan apa2 dari kata-katamu diatas.

Ya nggak usah dijelaskan nggak papa kok...

[dudulz]

seberapa panjangkah umur manusia di masa lalu...

hm...

klo untuk mengetahui ini apa bisa kita lihat dari dokumentasi2 sejarah?

klo dalam kisah2 seperti fengshen yanyi dan samkok ada banyak tokoh2 yg umurnya diceritakan sampai ratusan tahun dan tetap aktif dalam kehidupan politik/peperangan (=masih bugar)... bisa jadi dasar gak yah?

btw, krn topiknya sedang anthropogenesis, saya bawa 2 topik baru

1. Great leap forward

Advocates of this theory argue that the great leap forward occurred sometime 50-40kya in Africa or Europe. They argue that humans who lived before 50kya were behaviorally primitive and indistinguishable from other extinct hominids such as the Neanderthals or Homo erectus. Proponents of this view base their evidence on the abundance of complex artifacts, such as artwork and bone tools of the Upper Paleolithic, that appear in the fossil record after 50kya. They argue that such artifacts are absent from the fossil record from before 50kya, indicating that earlier hominids lacked the cognitive skills required to produce such artifacts.
Jared Diamond states that humans of the Acheulean and Mousterian cultures lived in an apparent stasis, experiencing little cultural change. This was followed by a sudden flowering of fine toolmaking, sophisticated weaponry, sculpture, cave painting, body ornaments, and long-distance trade.[11] Humans also expanded into hitherto uninhabited environments, such as Australia and Northern Eurasia.[11]
The Great Leap Forward was concurrent with the extinction of the Neanderthals, and it has been suggested that Cro-Magnon interaction with Neanderthals caused this extinction.
According to this model, the emergence of anatomically modern humans predates the emergence of behaviorally modern humans by over 100kya.


Modern humans and the "Great Leap Forward" debate

Until about 50,000–40,000 years ago the use of stone tools seems to have progressed stepwise. Each phase (habilis, ergaster, neanderthal) started at a higher level than the previous one; but once that phase started, further development was slow. In other words, these particular Homo species were culturally conservative. After 50,000 BP, however, human culture apparently started to change at a much greater speed. Jared Diamond, author of The Third Chimpanzee, and other anthropologists characterize this as a "Great Leap Forward." Modern humans started burying their dead carefully, making clothing out of hides, developing sophisticated hunting techniques (such as using trapping pits or driving animals off cliffs), and engaging in cave painting.[34] This speed-up of cultural change seems connected with the arrival of behaviorally modern humans, Homo sapiens. As human culture advanced, different populations of humans introduced novelty to existing technologies: artifacts such as fish hooks, buttons and bone needles show signs of variation among different populations of humans, something that had not been seen in human cultures prior to 50,000 BP. Typically, neanderthalensis populations are found with technology similar to other contemporary neanderthalensis populations.
Theoretically, modern human behavior is taken to include four ingredient capabilities: abstract thinking (concepts free from specific examples), planning (taking steps to achieve a further goal), innovation (finding new solutions), and symbolic behaviour (such as images and rituals). Among concrete examples of modern human behaviour, anthropologists include specialization of tools, use of jewelry and images (such as cave drawings), organization of living space, rituals (for example, burials with grave gifts), specialized hunting techniques, exploration of less hospitable geographical areas, and barter trade networks. Nevertheless, debate continues as to whether a "revolution" led to modern humans ("the big bang of human consciousness"), or whether the evolution was more gradual.[35]

(bersambung...)

[dudulz]

2. what's next? ada 2 pendapat menarik,

di the observer

For those who dream of a better life, science has bad news: this is the best it is going to get. Our species has reached its biological pinnacle and is no longer capable of changing.

That is the stark, controversial view of a group of biologists who believe a Western lifestyle now protects humanity from the forces that used to shape Homo sapiens.
'If you want to know what Utopia is like, just look around - this is it,' said Professor Steve Jones, of University College London, who is to present his argument at a Royal Society Edinburgh debate, 'Is Evolution Over?', next week. 'Things have simply stopped getting better, or worse, for our species.'
This view is controversial, however. Other scientists argue that mankind is still being influenced by the evolutionary forces that created the myriad species which have inhabited Earth over the past three billion years.
'If you had looked at Stone Age people in Europe a mere 50,000 years ago, you would assume the trend was for people to get bigger and stronger all the time,' said Prof Chris Stringer, of the Natural History Museum, London. 'Then, quite abruptly, these people were replaced by light, tall, highly intelligent people who arrived from Africa and took over the world. You simply cannot predict evolutionary events like this. Who knows where we are headed?'
Some scientists believe humans are becoming less brainy and more neurotic; others see signs of growing intelligence and decreasing robustness, while some, like Jones, see evidence of us having reached a standstill. All base their arguments on the same tenets of natural selection.
According to Darwin's theory, individual animals best suited to their environments live longer and have more children, and so spread their genes through populations. This produces evolutionary changes. For example, hoofed animals with longer necks could reach the juiciest leaves on tall trees and therefore tended to eat well, live longer, and have more offspring. Eventually, they evolved into giraffes. Those with shorter necks died out.
Similar processes led to the evolution of mankind, but this has now stopped because virtually everybody's genes are making it to the next generation, not only those who are best adapted to their environments.
'Until recently, there were massive differences between individuals' lifespans and fecundity,' said Jones. 'In London, the death rate outstripped the birth rate for most of the city's history. If you look at graveyards from ancient to Victorian times, you can see that a half of all children died before adolescence, probably because they lacked genetic protection against disease. Now, children's chances of reaching the age of 25 have reached 98 per cent. Nothing is changing. We have reached stagnation.'
In addition, human populations are now being constantly mixed, again producing a blending that blocks evolutionary change. This increased mixing can be gauged by calculating the number of miles between a person's birthplace and his or her partner's, then between their parents' birthplaces, and finally, between their grandparents'.
In virtually every case, you will find that the number of miles drops dramatically the more that you head back into the past. Now people are going to universities and colleges where they meet and marry people from other continents. A generation ago, men and women rarely mated with anyone from a different town or city. Hence, the blending of our genes which will soon produce a uniformly brown-skinned population. Apart from that, there will be little change in the species.
However, such arguments affect only the Western world - where food, hygiene and medical advances are keeping virtually every member of society alive and able to pass on their genes. In the developing world, no such protection exists.
'Just consider Aids, and then look at chimpanzees,' says Jones. 'You find they all carry a version of HIV but are unaffected by it.
'But a few thousand years ago, when the first chimps became infected, things would have been very different. Millions of chimps probably died as the virus spread through them, and only a small number, which possessed genes that conferred immunity, survived to become the ancestors of all chimps today.
'Something very similar could soon happen to humans. In a thousand years, Africa will be populated only by the descendants of those few individuals who are currently immune to the Aids virus. They will carry the virus but will be unaffected by it. So yes, there will be change there all right - but only where the forces of evolution are not being suppressed.'
However, other scientists believe evolutionary pressures are still taking their toll on humanity, despite the protection afforded by Western life. For example, the biologist Christopher Wills, of the University of California, San Diego, argues that ideas are now driving our evolution. 'There is a premium on sharpness of mind and the ability to accumulate money. Such people tend to have more children and have a better chance of survival,' he says. In other words, intellect - the defining characteristic of our species - is still driving our evolution.
This view is countered by Peter Ward, of the University of Washington in Seattle. In his book, Future Evolution, recently published in the US by Henry Holt, Ward also argues that modern Western life protects people from the effects of evolution. 'I don't think we are going to see any changes - apart from ones we deliberately introduce ourselves, when we start to bio-engineer people, by introducing genes into their bodies, so they live longer or are stronger and healthier.'
If people start to live to 150, and are capable of producing children for more than 100 of those years, the effects could be dramatic, he says. 'People will start to produce dozens of children in their lifetimes, and that will certainly start to skew our evolution. These people will also have more chance to accumulate wealth as well. So we will have created a new race of fecund, productive individuals and that could have dramatic consequences.
'However, that will only come about when we directly intervene in our own evolution, using cloning and gene therapy. Without that, nothing will happen.' Stringer disagrees, however. 'Evolution goes on all the time. You don't have to intervene. It is just that it is highly unpredictable. For example, brain size has decreased over the past 10,000 years. A similar reduction has also affected our physiques. We are punier and smaller-brained compared with our ancestors only a few millennia ago. So even though we might be influenced by evolution, that does not automatically mean an improvement in our lot.'

[dudulz]

di new york times

Providing the strongest evidence yet that humans are still evolving, researchers have detected some 700 regions of the human genome where genes appear to have been reshaped by natural selection, a principal force of evolution, within the last 5,000 to 15,000 years.


The genes that show this evolutionary change include some responsible for the senses of taste and smell, digestion, bone structure, skin color and brain function.
Many of these instances of selection may reflect the pressures that came to bear as people abandoned their hunting and gathering way of life for settlement and agriculture, a transition well under way in Europe and East Asia some 5,000 years ago.
Under natural selection, beneficial genes become more common in a population as their owners have more progeny.
Three populations were studied, Africans, East Asians and Europeans. In each, a mostly different set of genes had been favored by natural selection. The selected genes, which affect skin color, hair texture and bone structure, may underlie the present-day differences in racial appearance.
The study of selected genes may help reconstruct many crucial events in the human past. It may also help physical anthropologists explain why people over the world have such a variety of distinctive appearances, even though their genes are on the whole similar, said Dr. Spencer Wells, director of the Genographic Project of the National Geographic Society.
The finding adds substantially to the evidence that human evolution did not grind to a halt in the distant past, as is tacitly assumed by many social scientists. Even evolutionary psychologists, who interpret human behavior in terms of what the brain evolved to do, hold that the work of natural selection in shaping the human mind was completed in the pre-agricultural past, more than 10,000 years ago.
"There is ample evidence that selection has been a major driving point in our evolution during the last 10,000 years, and there is no reason to suppose that it has stopped," said Jonathan Pritchard, a population geneticist at the University of Chicago who headed the study.
Dr. Pritchard and his colleagues, Benjamin Voight, Sridhar Kudaravalli and Xiaoquan Wen, report their findings in today's issue of PLOS-Biology.
Their data is based on DNA changes in three populations gathered by the HapMap project, which built on the decoding of the human genome in 2003. The data, though collected to help identify variant genes that contribute to disease, also give evidence of evolutionary change.
The fingerprints of natural selection in DNA are hard to recognize. Just a handful of recently selected genes have previously been identified, like those that confer resistance to malaria or the ability to digest lactose in adulthood, an adaptation common in Northern Europeans whose ancestors thrived on cattle milk.
But the authors of the HapMap study released last October found many other regions where selection seemed to have occurred, as did an analysis published in December by Robert K. Moysis of the University of California, Irvine.
Dr. Pritchard's scan of the human genome differs from the previous two because he has developed a statistical test to identify just genes that have started to spread through populations in recent millennia and have not yet become universal, as many advantageous genes eventually do.
The selected genes he has detected fall into a handful of functional categories, as might be expected if people were adapting to specific changes in their environment. Some are genes involved in digesting particular foods like the lactose-digesting gene common in Europeans. Some are genes that mediate taste and smell as well as detoxify plant poisons, perhaps signaling a shift in diet from wild foods to domesticated plants and animals.
Dr. Pritchard estimates that the average point at which the selected genes started to become more common under the pressure of natural selection is 10,800 years ago in the African population and 6,600 years ago in the Asian and European populations.
Dr. Richard G. Klein, a paleoanthropologist at Stanford, said that it was hard to correlate the specific gene changes in the three populations with events in the archaeological record, but that the timing and nature of the changes in the East Asians and Europeans seemed compatible with the shift to agriculture. Rice farming became widespread in China 6,000 to 7,000 years ago, and agriculture reached Europe from the Near East around the same time.

Skeletons similar in form to modern Chinese are hard to find before that period, Dr. Klein said, and there are few European skeletons older than 10,000 years that look like modern Europeans.
That suggests that a change in bone structure occurred in the two populations, perhaps in connection with the shift to agriculture. Dr. Pritchard's team found that several genes associated with embryonic development of the bones had been under selection in East Asians and Europeans, and these could be another sign of the forager-to-farmer transition, Dr. Klein said.

Dr. Wells, of the National Geographic Society, said Dr. Pritchard's results were fascinating and would help anthropologists explain the immense diversity of human populations even though their genes are generally similar. The relative handful of selected genes that Dr. Pritchard's study has pinpointed may hold the answer, he said, adding, "Each gene has a story of some pressure we adapted to."

Dr. Wells is gathering DNA from across the globe to map in finer detail the genetic variation brought to light by the HapMap project.
Dr. Pritchard's list of selected genes also includes five that affect skin color. The selected versions of the genes occur solely in Europeans and are presumably responsible for pale skin. Anthropologists have generally assumed that the first modern humans to arrive in Europe some 45,000 years ago had the dark skin of their African origins, but soon acquired the paler skin needed to admit sunlight for vitamin D synthesis.
The finding of five skin genes selected 6,600 years ago could imply that Europeans acquired their pale skin much more recently. Or, the selected genes may have been a reinforcement of a process established earlier, Dr. Pritchard said.
The five genes show no sign of selective pressure in East Asians.
Because Chinese and Japanese are also pale, Dr. Pritchard said, evolution must have accomplished the same goal in those populations by working through different genes or by changing the same genes — but many thousands of years before, so that the signal of selection is no longer visible to the new test.
Dr. Pritchard also detected selection at work in brain genes, including a group known as microcephaly genes because, when disrupted, they cause people to be born with unusually small brains.
Dr. Bruce Lahn, also of the University of Chicago, theorizes that successive changes in the microcephaly genes may have enabled the brain to enlarge in primate evolution, a process that may have continued in the recent human past.
Last September, Dr. Lahn reported that one microcephaly gene had recently changed in Europeans and another in Europeans and Asians. He predicted that other brain genes would be found to have changed in other populations.
Dr. Pritchard's test did not detect a signal of selection in Dr. Lahn's two genes, but that may just reflect limitations of the test, he and Dr. Lahn said. Dr. Pritchard found one microcephaly gene that had been selected for in Africans and another in Europeans and East Asians. Another brain gene, SNTG1, was under heavy selection in all three populations.
"It seems like a really interesting gene, given our results, but there doesn't seem to be that much known about exactly what it's doing to the brain," Dr. Pritchard said.
Dr. Wells said that it was not surprising the brain had continued to evolve along with other types of genes, but that nothing could be inferred about the nature of the selective pressure until the function of the selected genes was understood.
The four populations analyzed in the HapMap project are the Yoruba of Nigeria, Han Chinese from Beijing, Japanese from Tokyo and a French collection of Utah families of European descent. The populations are assumed to be typical of sub-Saharan Africa, East Asia and Europe, but the representation, though presumably good enough for medical studies, may not be exact.
Dr. Pritchard's test for selection rests on the fact that an advantageous mutation is inherited along with its gene and a large block of DNA in which the gene sits. If the improved gene spreads quickly, the DNA region that includes it will become less diverse across a population because so many people now carry the same sequence of DNA units at that location.
Dr. Pritchard's test measures the difference in DNA diversity between those who carry a new gene and those who do not, and a significantly lesser diversity is taken as a sign of selection. The difference disappears when the improved gene has swept through the entire population, as eventually happens, so the test picks up only new gene variants on their way to becoming universal.
The selected genes turned out to be quite different from one racial group to another. Dr. Pritchard's test identified 206 regions of the genome that are under selection in the Yorubans, 185 regions in East Asians and 188 in Europeans. The few overlaps between races concern genes that could have been spread by migration or else be instances of independent evolution, Dr. Pritchard said.

[Swan]

seberapa panjangkah umur manusia di masa lalu...

hm...

klo untuk mengetahui ini apa bisa kita lihat dari dokumentasi2 sejarah?

klo dalam kisah2 seperti fengshen yanyi dan samkok ada banyak tokoh2 yg umurnya diceritakan sampai ratusan tahun dan tetap aktif dalam kehidupan politik/peperangan (=masih bugar)... bisa jadi dasar gak yah?

btw, krn topiknya sedang anthropogenesis, saya bawa 2 topik baru

1. Great leap forward

Advocates of this theory argue that the great leap forward occurred sometime 50-40kya in Africa or Europe. They argue that humans who lived before 50kya were behaviorally primitive and indistinguishable from other extinct hominids such as the Neanderthals or Homo erectus. Proponents of this view base their evidence on the abundance of complex artifacts, such as artwork and bone tools of the Upper Paleolithic, that appear in the fossil record after 50kya. They argue that such artifacts are absent from the fossil record from before 50kya, indicating that earlier hominids lacked the cognitive skills required to produce such artifacts.
Jared Diamond states that humans of the Acheulean and Mousterian cultures lived in an apparent stasis, experiencing little cultural change. This was followed by a sudden flowering of fine toolmaking, sophisticated weaponry, sculpture, cave painting, body ornaments, and long-distance trade.[11] Humans also expanded into hitherto uninhabited environments, such as Australia and Northern Eurasia.[11]
The Great Leap Forward was concurrent with the extinction of the Neanderthals, and it has been suggested that Cro-Magnon interaction with Neanderthals caused this extinction.
According to this model, the emergence of anatomically modern humans predates the emergence of behaviorally modern humans by over 100kya.


Modern humans and the "Great Leap Forward" debate

Until about 50,000–40,000 years ago the use of stone tools seems to have progressed stepwise. Each phase (habilis, ergaster, neanderthal) started at a higher level than the previous one; but once that phase started, further development was slow. In other words, these particular Homo species were culturally conservative. After 50,000 BP, however, human culture apparently started to change at a much greater speed. Jared Diamond, author of The Third Chimpanzee, and other anthropologists characterize this as a "Great Leap Forward." Modern humans started burying their dead carefully, making clothing out of hides, developing sophisticated hunting techniques (such as using trapping pits or driving animals off cliffs), and engaging in cave painting.[34] This speed-up of cultural change seems connected with the arrival of behaviorally modern humans, Homo sapiens. As human culture advanced, different populations of humans introduced novelty to existing technologies: artifacts such as fish hooks, buttons and bone needles show signs of variation among different populations of humans, something that had not been seen in human cultures prior to 50,000 BP. Typically, neanderthalensis populations are found with technology similar to other contemporary neanderthalensis populations.
Theoretically, modern human behavior is taken to include four ingredient capabilities: abstract thinking (concepts free from specific examples), planning (taking steps to achieve a further goal), innovation (finding new solutions), and symbolic behaviour (such as images and rituals). Among concrete examples of modern human behaviour, anthropologists include specialization of tools, use of jewelry and images (such as cave drawings), organization of living space, rituals (for example, burials with grave gifts), specialized hunting techniques, exploration of less hospitable geographical areas, and barter trade networks. Nevertheless, debate continues as to whether a "revolution" led to modern humans ("the big bang of human consciousness"), or whether the evolution was more gradual.[35]

(bersambung...)

Mau jelasin panjang lebar tentang Umur manusia lewat sejarah masa lalu, aku rada males dulz. Soalnya aku malah dibalik tanya sama mas bim2. Tapi yang jelas aku percaya, lewat penelitian sejarah yang udah ada, manusia jaman dulu memang lebih berumur panjang daripada manusia sekarang. Nah hal ini yang buat aku menyimpulkan kalau evolusi nggak berlaku. Perubahan dimasa yang akan datang lebih "mundur" dibandingkan masa lalu. Baik itu umur maupun kesehatan. Mungkin dikarenakan teknologi yang semakin maju pesat.

[dudulz]

.... Baik itu umur maupun kesehatan. Mungkin dikarenakan teknologi yang semakin maju pesat.

yakakak, wah swan, gw pake artikel panjang lebar lu cuman satu kalimat doang. sama lah intinya... dengan tambahan artikel dengan sudut pandang lain sebagai pembanding...

[Swan]

yakakak, wah swan, gw pake artikel panjang lebar lu cuman satu kalimat doang. sama lah intinya... dengan tambahan artikel dengan sudut pandang lain sebagai pembanding...

Lha ya itu yang intinya aku tanya sama Mr.bimbim. tapi eh dia nya balik tanya ke aku....

[bimbim]

data-data umur manusia diambil dari peradaban manusia yg paling kuno yg masih tercatat yg ada di dalam sejarah Mesir kuno yg tercatat dalam Hieroglief menunjukkan rata-rata umur laki-laki adalah 54 tahun, dan rata-rata umur wanita adalah 58 tahun.

bisa dibaca di: Old Age in Ancient Egypt

ayo cari data-data nya kawan, biasakan mencari data kongkrit sebelum posting.