How Old is the Earth?

[Laudate_Dominum]

My ancient posts on this thread seem a bit funny to me now, but I'm actually more convinced than ever that neanderthal was human and has an immortal soul. I believe that neanderthal was largely wiped out by disease epidemics brought by migrating homo sapiens who had a more robust immune system. I'm even of the view that a remnant neanderthal population was assimilated and that the gene that causes red hair in modern humans is a trace of the neanderthal still kicking.

I'm also still pretty serious about the status of homo erectus as well as the gap between homo and australopithecus fossils.

It's interesting stuff anyway.

[EcceNovaFacioOmni]

[quote name='Laudate_Dominum' post='1011684' date='Jun 24 2006, 06:31 PM']
My ancient posts on this thread seem a bit funny to me now, but I'm actually more convinced than ever that neanderthal was human and has an immortal soul. I believe that neanderthal was largely wiped out by disease epidemics brought by migrating homo sapiens who had a more robust immune system. I'm even of the view that a remnant neanderthal population was assimilated and that the gene that causes red hair in modern humans is a trace of the neanderthal still kicking.

I'm also still pretty serious about the status of homo erectus as well as the gap between homo and australopithecus fossils.

It's interesting stuff anyway.
[/quote]
Actually, there are scientists who believe Neanderthals to have been a subspecies of Homo sapiens. Either way, Neanderthal DNA has not been found in any modern humans.

In regards to red hair, there are some scientists who would agree with you but, from what I can tell, it is not widely accepted. I have red hair, by the way. I wonder if I have some Neanderthal in me!

[Theoketos]

[quote name='Theoketos' post='713304' date='Sep 6 2005, 01:07 PM']
I woke up dreaming about this thread with the following thought in my head:

Since God created all of this ex nihilo (from nothing) could He have not created the Universe in the certain state of decay? In other words...When God created the Universe it was created to be x billions of years old already?
[/quote]

Um maybe not, because that seems deceitful and God would not deceive us.

And also, I think that John Paul II said it well:

ADDRESS OF POPE JOHN PAUL II
TO THE PARTICIPANTS
IN THE VATICAN CONFERENCE ON COSMOLOGY

Saturday, 6 July 1985



Dear Friends,

1. Offer very cordial greetings to the participants in the Vatican Conference on Cosmology. In this year which marks the Fiftieth Anniversary of scientific research at the Specola Vaticana, I would like to take this occasion to extend my heartfelt congratulations and best wishes to Father Coyne and the entire staff of the Observatory. Please know that your diligent work, especially in the field of astrophysics, together with your ecclesial dedication, bears splendid witness to the Church’s profound interest in the world of science and particularly in the men and women engaged in scientific research.

I warmly greet the observational astronomers and the theorists in gravitational physics and cosmology who have accepted the invitation to take part in this important meeting. It is a joy to welcome you today, together with the members of your families.

2. Through the natural sciences, and cosmology in particular, we have become much more aware of our true physical position within the universe, within physical reality - in space and in time. We are struck very forcibly by our smallness and apparent insignificance, and even more by our vulnerability in such a vast and seemingly hostile environment. Yet this universe of ours, this galaxy in which our sun is situated and this planet on which we live, is our home. And all of it in some way or other serves to support us, nourish us, fascinate us, inspire us, taking us out of ourselves and forcing us to look far beyond the limits of our unaided vision. What we discover through our study of nature and of the universe in all its immensity and rich variety serves on the one hand to emphasize our fragile condition and our littleness, and on the other hand to manifest clearly our greatness and superiority in the midst of all creation - the profoundly exalted position we enjoy in being able to search, to imagine and to discover so much. We are made in the image and likeness of God. Thus, we are capable of knowing and understanding more and more about the universe and all that it contains. We can reach out and grasp its inner workings and designs, plumbing its depths with questioning reverence and with awestruck imagination.

3. This Conference, I have been told, has as one of its principal focuses the determination of the inherent limitations of cosmology’s competency and its observational verifiability - the limits in principle and in practice of the scientific verification of its theoretical products. With a gradual and constant growth in humble self-knowledge, we are able to avoid the extremes of an inflated evaluation of our own abilities and capacities or a disparagingly narrow and superficial one. And that is true of any disciple or field of study. A sound appreciation of both our limitations and strong points enables us to plan our projects carefully, to maintain proper relationships with the material, personal and divine realities, and to become ever more sensitive to all the valuable information which is available to us through modern science.

4. The more we know about physical reality, about the history and structure of the universe, about the fundamental make-up of matter and the processes and patterns which at the roots of the material world, the more we can appreciate the immensity of the mystery of God, the more we are in a position to grasp the mystery of ourselves - our origin and our destiny. For creation, as we have come to know it, speaks to us in fragmentary yet very true reflections of the God who created it and maintains it in existence. Of course, that picture must always remain tantalizingly incomplete. For certain aspects of our lives rise above and move beyond the material dimension and, while having deep roots in the material, surpass the understanding which the natural sciences are capable of providing. They draw our attention to the realm of the Spirit. The human creations of art and poetry, our longing for justice and peace and for wholeness, indeed all genuine human experience, lead us to recognize that there is an interiority in the universe and particularly in human life, an interiority which cannot simply be reduced to the features of reality which the physical and natural sciences are concerned with. There are certainly important and essential contributions to be made by the sciences, directly and indirectly, to these more interior or spiritual characteristics of reality. Indeed such contributions must be made, but their investigation and study demands other complementary methods and disciplines such as those provided by the arts, the humanities, philosophy and theology. These in turn must become aware of their own essential competencies and limitations.

5. Much of what modern astronomy and cosmology investigate does not find direct application via technology. Yet it makes a vitally important contribution. For it helps us, at the very least, to put ourselves and everything else into a larger perspective, encouraging us to move beyond our own narrow and selfish concerns. Our view of ourselves, of God and of the universe is radically different from that of people in the Middle Ages. We see ourselves situated in a much larger context - in a much more vast and much more intricately, even delicately, complex world and universe.

For the first time we have seen ourselves from outside - from the Moon, and from other vantage points in our solar system. And with that startling perspective, we realize that we must be more responsible for ourselves, our neighbours, our institutions, and our planet, whatever may be our nation, religion or political stance. We realize ever more deeply our smallness and our frailty, but at the same time our grandeur. We feel more inclined to say together with the Psalmist of the Old Testament: “The heavens proclaim the glory of God and the firmament shows forth the work of his hands” (Ps. 19 (18), 1.

[url="http://www.vatican.va/holy_father/john_paul_ii/speeches/1985/july/documents/hf_jp-ii_spe_19850706_conferenza-cosmologia_en.html"]http://www.vatican.va/holy_father/john_pau...mologia_en.html[/url]

[Moore86]

[quote name='MC Just' post='655536' date='Jul 23 2005, 05:47 AM']
How old is the earth?
[/quote]

I have no idea, but I guess a safe answer would be, only God knows. : :

[cmotherofpirl]

[color="#33CCFF"]This was an interesting show on recently:[/color]

Documentary Redraws Humans' Family Tree
Hillary Mayell
for National Geographic News


By analyzing DNA from people in all regions of the world, geneticist Spencer Wells has concluded that all humans alive today are descended from a single man who lived in Africa around 60,000 years ago.

Modern humans, he contends, didn't start their spread across the globe until after that time. Most archaeologists would say the exodus began 100,000 years ago—a 40,000-year discrepancy.

Wells's take on the origins of modern humans and how they came to populate the rest of the planet is bound to be controversial.

His work adds to an already crowded field of opposing hypotheses proposed by those who seek answers in "stones and bones"—archaeologists and paleoanthropologists—and those who seek them in our blood—population geneticists and molecular biologists.


Over the last decade, major debate on whether early humans evolved in Africa or elsewhere, when they began outward migration, where they went, and whether they interbred with or replaced archaic species has moved out of scientific journals and into the public consciousness.

Wells addresses these issues in a new book, The Journey of Man: A Genetic Odyssey, and a National Geographic documentary of the same title. In a straightforward story, he explains how he traced the exodus of modern humans from Africa by analyzing genetic changes in DNA from the y-chromosome.

"As often happens in science," he said, "technology has opened up a field to new ways of answering old questions—often providing startling answers."

Of course, not everyone agrees with him.

Search for Origins

The use of population genetics and molecular biology in human origins research has been extremely important in helping to resolve a long-running debate on where modern humans first evolved.

According to the multi-regional model, an archaic form of humans left Africa between one and two million years ago, and modern humans evolved from them independently and simultaneously in pockets of Africa, Europe, and Asia.

Wells's work and that of others confirms the more widely accepted Out of Africa model, which says that all modern humans evolved in Africa and then left in several waves of migration, ultimately replacing any earlier species.

"Genetic evidence tells us that Homo sapiens are of recent origin and arose in Africa," said S. Blair Hedges, a molecular biologist at Pennsylvania State University.

"African populations have the most ancient alleles [gene pairs that code for specific traits] and the greatest genetic diversity, which means they're the oldest," Hedges explained. "Our species probably had arisen by 150,000 years ago, with a population of perhaps 10,000 individuals."

Chris Stringer, director of the Human Origins Program at the Natural History Museum in London, said: "The multi-regional model of Homo sapiens evolving globally over a long time scale is certainly dead."

Whether archaic humans and modern humans interbred is another point of debate.

"Given the uncertainties, it isn't yet possible to establish whether we are entirely recent African in origin—certainly my preference—or whether there was a little bit of hybridization/assimilation" between modern and archaic species," said Stringer.

Wells says there is no genetic evidence that supports the idea of intermixing, and several DNA studies actually argue strongly against it.

Journey of Man

Today, there is general agreement that Homo erectus, the precursor to modern humans, evolved in Africa and gradually expanded to Eurasia beginning about 1.7 million years ago.

By around 100,000 years ago, several species of hominids populated the Earth, including H. sapiens in Africa, H. erectus in Southeast Asia and China, and Neandertals in Europe.

By around 30,000 years ago, the only surviving hominid species was H. sapiens.

But when did we leave Africa and where did we go? Here's where opinions diverge widely.

Wells says his evidence based on DNA in the Y-chromosome indicates that the exodus began between 60,000 and 50,000 years ago.

In his view, the early travelers followed the southern coastline of Asia, crossed about 250 kilometers [155 miles] of sea, and colonized Australia by around 50,000 years ago. The Aborigines of Australia, Wells says, are the descendants of the first wave of migration out of Africa.

Many archaeologists disagree, saying the fossil record shows that a first wave of migration occurred around 100,000 years ago.

"Archaeological evidence suggests that there were modern humans in at least two places in the Levant region of the Middle East 90,000 years ago," said Alison Brooks, a paleoanthropologist at George Washington University in Washington, D.C. "They disappear from the Levant about 10,000 years later, but could have survived further south in Asia—we just have no evidence."

"There's also evidence," she added, "of Homo sapiens in Australia 60,000 years ago, and they'd have to go through India and Southeast Asia to get there."

Wells agrees that there may have been early human forays into the Middle East, but argues that the Levant of 100,000 to 150,000 years ago was essentially an extension of northeastern Africa and was probably part of the original range of early Homo sapiens. These early settlers were replaced by Neandertals in the region about 80,000 years ago.

"There's a roughly 30,000-year gap in the archaeological record of Homo sapiens outside of Africa," said Wells. "The real expansion occurred in the Upper Paleolithic (around 40,000 years ago) into the uncharted territory of Asia proper."

Brooks agrees there's a gap, but puts it closer to 20,000 years.

Richard Klein, an anthropologist at Stanford University, has one explanation for the gap and the subsequent waves of colonization beginning around 45,000 years ago.

Klein thinks Homo sapiens may have been anatomically modern 150,000 years ago, but did not become behaviorally modern until about 50,000 years ago, when a genetic mutation related to cognition made us smarter.

He theorizes that this change in thinking ability enabled modern humans to craft sophisticated tools, build permanent lodgings, hunt more effectively, and possibly develop language. It also led to greater travel.

Other possible triggers for the burst of migration 45,000 years ago include an increase in population, which spurred competition and innovation; a change in diet, with consumption of more meat and fish; the acquisition of language; and climate change.

Populating the Globe

Wells says a second wave of hominids left Africa around 45,000 years ago, reproduced rapidly, and settled in the Middle East; smaller groups went off to India and China.

Isolated by mountains and the sea for many generations, and exposed to a colder climate and less sunlight than in Africa, the Asian populations became paler over time.

Around 40,000 years ago, as the grip of the Ice Age loosened and temperatures briefly became warmer, humans moved into Central Asia. Amid the bountiful grassy steppes, they multiplied quickly.

"If Africa was the cradle of mankind, then Central Asia was its nursery," said Wells.

Around 35,000 years ago, small groups left Central Asia for Europe. Cold temperatures kept them there. Cut off from other groups, these migrants became paler and shorter than their African ancestors.

From there, around 20,000 years ago, another small group of Central Asians moved farther north, into Siberia and the Arctic Circle. To minimize physical exposure to the extreme cold they developed, over many generations, stout trunks, stubby fingers, and short arms and legs.

Finally, around 15,000 years ago, as another Ice Age began to wane, one small clan of Arctic dwellers followed the reindeer herd over the Bering Strait land bridge into North America.

According to the genetic data, says Wells, this initial group may have included as few as two or three men—perhaps 10 to 20 people in all. Also isolated, they too acquired distinct physical characteristics.

Many archaeologists, however, believe that Australia, the Middle East, India, and China were inhabited much earlier.

"The dates don't compare well to the order or the geography of the migration patterns revealed by the fossil record," said Brooks. "Y-chromosome data give consistently younger dates than other types of genetic data, such as mitochondrial DNA."

Hedges said that "the dates of expansion and colonization discussed by Wells may be correct, but they almost appear to be too recent. Most geneticists are getting data that agree with most archaeological and fossil data." He noted, however, that all of the different methods used for dating can generate errors.

"If you step back a bit and look at the bigger picture, there is a lot more agreement in this field today than there was a decade ago," Hedges said.

Common Ancestors

Wells's work is based on studies of DNA in the y-chromosome. The y-chromosome is a good candidate for population studies such as this because it doesn't recombine as other parts of the genome do (each parent contributes half of a child's DNA, which join together to form a new genetic combination).

Thus, the y-chromosome is passed on as a chunk of DNA from father to son, basically unchanged through generations except for random mutations.

These random mutations, which can happen naturally and be harmless, are called markers. Once a marker has been identified, geneticists can go back in time and trace it to the point at which it first occurred, which would be the most recent common ancestor.

As in any scientific work, there are caveats.

The point at which a single common ancestor is found "can vary based on which gene you're looking at, the mutation rate, and population size, and on factors such as whether a bottleneck in the population occurred," said Sarah Tishkoff, a geneticist at the University of Maryland. "Natural selection also plays a significant role."

There is another chunk of DNA that also passes through generations relatively unchanged; it is found in a part of the cell called the mitochondria and is transferred from mother to daughter.

While the most recent male common ancestor identified through the y-chromosome lived 60,000 years ago, the most recent female common ancestor traced through mitochondrial DNA lived around 150,000 years ago. Whether an individual can be identified as our single common ancestor is open to debate.

"There's almost certainly not an Adam or Eve," said Tishkoff. "Each of our genes have their own history, which could be passed on from different ancestors. It's more likely that a lineage can be traced back to a population of 50, 100, or even several thousand people."

Others agree.

"The fact that one man apparently gave rise to the y-chromosome genes of all moderns does not mean he was our only male ancestor," said Stringer. "What it means is that his male progeny were more prolific breeders or luckier, and their Y genes survived while those of his contemporaries didn't. But those contemporaries could have passed on many other genes to present-day peoples."

That's "absolutely correct," said Wells, adding: "The real significance of the date of our common Y-chromosome ancestor, is that it effectively gives us an upper limit on when our species began to leave Africa."

One point of wide agreement among those who study human origins is that more and more insight will come from closer collaboration between disciplines

"Greater discussion and collaboration between geneticists and paleoanthropologists would be good for both," said Stringer.

"It's worth bearing in mind," he said, "that studies of recent DNA are studies of the genes of the survivors. Such studies can't tell us anything about non-survivors, such as the Neandertals and Solo Man in Java. We still require fossils, archaeology, and, where possible, ancient DNA for the whole picture of human evolution."

Wells's work described in Journey of Man draws on genetics, palaeoanthropology, palaeoclimatology, archaeology, psychology, and linguistics.

"I really see the field as a collaborative, synthetic effort to make sense of our past," he said. "The notion that any single area of investigation, operating in isolation, could have all the answers is ludicrous."

[heavenseeker]

about 4 billion years