Origins of Homo Sapiens

When I first became interested in Human Origins, back in the 1960s, the only known ancestors were: the Neanderthals, Homo Erectus, Homo Habilis and Australopithecus Africanus. Over the last 50 years an enormous amount if information has been found by scientific researchers. The story of human origins has become more complex and much more interesting.

The series of videos in this post give an excellent summary of the of the current understanding of the field.

The only issues left out are the Denisovans , Homo floresiensis and the Red Dear Cave People These are fairly recent findings and are still enigmatic so it is not surprising that they have been left out. These three groups, though, support the possibility that non-modern humans persisted until relatively recent times.

Thank you to Black Ryder Films for producing this great series.

Here is a link to a documentary series on Darwin.

The Genius of Charles Darwin

This is a three part series by Richard Dawkins, on one of the greatest scientists of all time - Charles Darwin.

It covers Darwin's life, theory and the amazing and absurd opposition to evolution.

In the series Dawkins has two main objectives: arguing the undeniable evidence for evolution and attacking religious belief. In the first episode he works with a science class in a school. He runs across religiously based opposition from some of the students. I would have taken a more accommodationist approach and said something like: "This is a science class and I am not going to oppose your religious beliefs. It is possible to believe in God and also evolution." Dawkins is naturally aware of this argument as he discusses it with the Archbishop of Canterbury in the third episode. Dawkins has very reasonable objections to the argument, but it is not relevant in science class. Once the religiously minded kids accepted basic science they might come around to Lawrence Krauss's position, which I agree with) : So while scientific rationality does not require atheism, it is by no means irrational to use it as the basis for arguing against the existence of God.

I am sure that Dawkins would see my position as a cop out.

The desperate pig ignorance of the creationists in the third episode is amazing. These people have not the slightest interest in truth or honesty. They smilingly talk nonsense and tell outright lies. Talking to such people is like talking to climate deniers - a total waste of time - because evidence, reason and logic are irrelevant to them.

How do you know?

Recently a very good friend of mine claimed that the recent volcano in South America put out more carbon dioxide that humans did in a year. I tried to explain to him that this claim was not true and that my source was the United States Geological Union who were experts on geological issues. Here is a link to the source that I quoted. (Note that the web page gives a link to a recent article on this issue).

This conversation highlighted to me the issue of sources of information. There is an enormous amount of misinformation currently in circulation. How does the sort of misinformation claimed by my friend get so widely disseminated? I think the reason is that when people hear ideas that they agree with they don't bother to check out the validity of the idea of the reliability of the source.

The video below by Peter Harfield, who produces the potholer54 channel of on YouTube discusses the importance of checking sources of claims that are made in the media.



I first became aware of this issue of sources when reading an online article by Andrew Bolt in 2006. the article was on Al Gore's film An Inconvenient Truth. The article can be found here.

The article was online so I started researching using Google. I fairly quickly started to have doubts about Bolt's claims.

Bolt's first objection was this one:

1: Gore claims that a survey of 928 scientific articles on global warming showed not one disputed that man's gasses were mostly to blame for rising global temperatures. Only dumb journalists and bad scientists in the pay of Big Oil pretended there was any genuine debate.

In fact, as Dr Benny Peiser, from Liverpool John Moores University has demonstrated, Gore relies on a bungled survey reported in Science.

The first article that I found was here.

It appeared that Peiser was finding difficulty maintaining the claims that Bolt relied on.

I then came across this email communication. In it Peiser seems to retract his major claim and at the finish notes:

I do not think anyone is questioning that we are in a period of global warming. Neither do I doubt that the overwhelming majority of climatologists is agreed that the current warming period is mostly due to human impact.

That, of cause is not the sort of message that Andrew Bolt tries to give on his site.

I then checked out Bolt's third criticism:

3: Gore says ice cores from Antarctica, that go back 650,000 years, show the world got warmer each time there was more carbon dioxide in the air.

In fact, as the University of California's Professor Jeff Severinghaus and others note, at least three studies of ice cores show the earth first warmed and only then came more carbon dioxide, many hundreds of years later. So does extra carbon dioxide cause a warming world, or vice versa?

I Googled Severinghaus and first I found articles about rapid warming in Greenland. I eventually found articles that discussed the last deglaciation, including this one. In these articles and in an email reply to me Seveinghaus emphasised that carbon dioxide was very important in the last deglaciation, providing between 35% and 50% of the warming. I later found this article where Severinghaus cries foul on Bolt's reporting.

When I returned to Bolt's article and re-read his point 3 I realised that Bolt had not directly stated that Severinghaus agreed with Bolt's interpretation, so technically Bolt had not mislead his readers. But most people who read the article would expect that the expert that he referenced would agree with Bolt's argument - and the expert clearly does not agree with Bolt's argument.

After that experience, I realised that it was very important to check the sources of claims that are made in the media, which is the point that Peter Harfield is making in his video.

Design Vs Chance

Human Origins

Introduction

As the name indicates, the video below is a quick introduction to Human Origins.



The video is one of about 25 that can be found on this web page (about half way down).

Humans and the Great Apes

Some confused people want to claim that according to evolutionary theory Humans evolved from Chimpanzees. This is not the view of scientists. The diagram below shows the general view of the relationship between the human line and the chimpanzee line. About 6 million years ago there lived a creature part of whose population started to evolve in the direction of chimpanzees and another part of whose pouplation began to evolve in the direction of humans. That creature is the Last Common Ancestor (LCA) of Humans and Chimps. The amount of time ago that the creature lived is estimated by the molecular clock. See also this article, which indicates that 6 million years ago is very likely an upper limit to the time of the LCA, which might well be a million years or so closer to the present.

A major problem is that scientists have found few fossils along the branch leading to Chimpanzees. The hominid line leading to us, on the other hand, currently has about 19 species populating it, as shown by the diagram below. (Click on the diagram for an enlargement, in a new window or tab.)


Another way of graphically viewing the hominid fossils is via this interactive timeline, which contains links to articles on the different species.

The Hominids I won't discuss all of the 20 or so hominid species as that would lead to a very long and tedious post. This link has summaries of the hominids (and it is still fairly long). At the right there are links to the hominid species (mostly links to Wikipedia articles). Sahelanthropus tchadensis Here is a link to a photograph of the fossil cranium. Fossils of this species date probably to almost 7 million years ago. There is considerable debate about this creature.    Some experts, including its discoverers, think that it has remarkably modern features, such as its flat face and indications that it was bipedal. The problem with this is that Sahelanthropus' age makes it comtemporaneous or possibly older than the LCA. It might be that the LCA was much more human like that previously expected. On the other hand, there is some uncertainty about the stratiography of the find, and the fossil might be less than 7 million years old. As well some experts are unconvinced about its modern features - see this link for an such an opinion. More fossil evidence will be required to resolve these issues. The discoverers of Sahelanthropus have many more fossils, some of which might help to clarify the status of the creature, which might include clarification of the nature of the LCA. Here is the website of the discoverers, giving their opinion of the fossil. Orrorin tugenensis Here is a link to a graphic of the Orrin fossils, which are between 6.2 and 5.6 million years old. The discoverers claim that Orrorin was bipedal, and there are indications that this was true, but that issue has not been tied down conclusively. The creature was about the size of a modern Chimpanzee.

Links to articles on Hominids    Sahelanthropus tchadensis    Orrorin tugenensis    ArdiPithecus kadaba    Ardipithecus ramidus     Australopithecus anamensis    Australopithecus afarensis     Kenyanthropus platyops    Australopithecus africanus    Australopithecus garhi    Australopithecus sediba    Australopithecus aethiopicus    Australopithecus robustus     Australopithecus boisei     Homo habilis     Homo georgicus     Homo erectus     Homo antecessor     Homo heidelbergensis     Homo neanderthalensis     Homo floresiensis    X-woman

Ardipithecus ramidus A few Ardipithecus ramidus fossils were found in 1990 but the motherload as pictured at right was found in 1994. The fossil was very fragile and took a great deal of expertise, care and time to extract. It also took a great deal of time to preserve, reconstruct and analyse it, and it was not until 2009 that comprehensve papers were published on Ardi. The papers covering the fossil evidence as well as environment that Ardi inhabited and its place in human history can be downloaded from this link. Ardi is about 4.4 million years old. The reconstructed scull is similar to Sahelanthropus tchadensis, and is about the size of a Chimpanzee. The useful summary below is found at this site: Ar. ramidus was quadrupedal in the trees, walking along branches using the palms of their hands, as many monkeys do, (i.e. they weren't hanging from branches or climbing with a vertical torso like modern apes do). It is also claimed by its discoverers that ramidus was bipedal on the ground, though not nearly as well adapted to it as humans are. (This particular claim is being treated cautiously so far; a few important scientists have expressed reservations about it.) The foot of ramidus had a widely divergent big toe for grasping while climbing (like chimps), but lacks the extreme feet flexibility of chimps which allows them to mold their feet around objects. ramidus also has none of the anatomical specializations of chimps for knucklewalking when on the ground. The Ar. ramidus pelvis was very ape-like in the lower pelvis, but had changes in the upper pelvis which made it an effective upright walker. It is more primitive than the pelvis of australopithecines, which were almost fully adapted to bipedality.

Evolution of Whales

That whales evolved from fully terrestrial (land) animals seems at first sight unlikely, but the evidence for that view is overwhelming. Like many other areas of strong science there are mulitple independent lines of evidence supporting the arguments of the scientists. A good source of information is from the article The Origin of Whales and the Power of Independent Evidence , written by Raymond Sutera.

In the case of whales the independent lines of evidence number nine.

1. Paleontological evidence
Scientists have identified a number of fossil creatures that make up the lineage of whale. In chronological order, these include: Sinonyx (60 million years ago), Pakicetus (52 million years ago), Ambulocetus (50 million years ago), Rodhocetus (46-7 million years ago), Basilosaurus (35-45 million years ago), Dorudon (about 40 million years ago).

As Raymond Sutera states:


... we have noted the consistent changes that indicate a series of adaptations from more terrestrial to more aquatic environments as we move from the most ancestral to the most recent species. These changes affect the shape of the skull, the shape of the teeth, the position of the nostrils, the size and structure of both the forelimbs and the hindlimbs, the size and shape of the tail, and the structure of the middle ear as it relates to directional hearing underwater and diving. The paleontological evidence records a history of increasing adaptation to life in the water - not just to any way of life in the water, but to life as lived by contemporary whales.

2. Morphological evidence

Morphology is the study of the form and structure of organisms and their specific structural features.

The study of the form and structure of the creatures described in the previous section further strengthen the view that they were ancestral to modern whales. These structures include: the anatomy of the foot of Basilosaurus allies and the "anvil" of the middle ear of Pakicetus.

3. Molecular biological evidence

Sutera explains how molecular biology can be used to determine evolutionary lineages as follows:

The hypothesis that whales are descended from terrestrial mammals predicts that living whales and closely related living terrestrial mammals should show similarities in their molecular biology roughly in proportion to the recency of their common ancestor. That is, whales should be more similar in their molecular biology to groups of animals with which they share a more recent common ancestor than to other animals that exhibit convergent similarities in morphology, ecology, or behavior.

The chart below summarises the results of such molecular biological studies.



Whales are not only related to the ungulates, they fit right in the middle of that group. This evidence not only supports the view that the ancestors of whales were terrestrial animals but also points to the animals closest to whale ancestors - hippos.

4. Vestigial evidence

Vestigial features are anatomical features that are of no use to a creature, although they take energy to maintain.

Whales have vestigial features that point clearly to their terrestrial origin. Vestigial features of modern whales include: very small pelvic and back leg bones embedded within their bodies, olfactory nerves even though whales have no sense of smell, vestiges of ears designed to hear in air and a vestigial diaphram.

5. Embryological evidence

Sutera notes:

... the embryology of the whale, examined in detail, also provides evidence for its terrestrial ancestry. As embryos no less than as adult animals, whales are junkyards, as it were, of old, discarded features that are of no further use to them. Many whales, while still in the womb, begin to develop body hair. Yet no modern whales retain any body hair after birth, except for some snout hairs and hairs around their blowholes used as sensory bristles in a few species. The fact that whales possess the genes for producing body hair shows that their ancestors had body hair. In other words, their ancestors were ordinary mammals.

6. Geochemical evidence

Like most elements, Oxygen comes in a number of different varieties, called isotopes. See this link for details. As can be seen from the article at the link, fresh water has a slightly higher concentration of lighter oxygen than does sea water. These slightly different isotopic ratios are recorded in the bones of animals, so those that drank fresh water can be differentiated from those that drank sea water. fossil teeth from the earliest whales have lower ratios of heavy oxygen to light oxygen, which shows that those animals drank fresh water. Later fossil whale teeth have higher ratios of heavy oxygen to light oxygen, indicating that they drank salt water. This absolutely reinforces the inference drawn from all the other evidence discussed here: the ancestors of modern whales adapted from terrestrial habitats to saltwater habitats by way of freshwater habitats. (Sutera)

7. Paleoenvironmental evidence

Paleoenvironmental evidence refers to the other fossils found in the same beds as the target fossil type as well as the types of rock bed that the fossils were found in. The whale ancestors that were clearly terrestrial (from their morphology) are also associated with fossils of terrestrial organisms, as well as with terrestrial rock types. The whale ancestors whose morphology shows that they were marine were assiciated with fossils of marine organisma and marine rock types.

8. Paleobiogeographic evidence

Paleobiogeographic evidence refers to the geographic distribution of fossils. We would expect that the terrestrial ancestors would have a limited geographical range, whilc later marine ancestors, who had the oceans to populate, would have a wider geographic range. The locations of the different whale ancestors follow these expectations.

9. Chronological evidence

Chronological evidence refers to the reason why whales appeared when they did.

Whales are mammals and could not have radiated before the Cretaceous–Tertiary extinction event (which happened 65 million years ago) as the seas at that time were filled with marine reptiles such as the plesiosaurs, ichthyosaurs, mosasaurs, and marine crocodile. When these fearsome predators, and many other marine creatures, went extinct there were plenty of environmental niches for whales (and other mammals) to expand into. The transition from terrestrial animals to deep-diving whales with directional underwater hearing took about 10 - 15 million years.

Conclusion

The evidence that whales evolved from terrestrial ancestors is supported by many mutually reinforcing, independent lines of evidence. Any attempt to discredit this conclusion has to deal with all of this independent evidence, which creationists have spectacularly failed to do.

                  ________________________________

There are two types of whale: toothed whales and baleen whales. The evidence shows that baleen whales evolved from toothed whale ancestors about 30 million years ago. Here is an article on a transitional fossil between toothed whales and baleen whales.

                  ________________________________

The five videos below together make up a fascinating documentary on the evolution of whales:

Dawkins on Evolution

Flagellum

Some Christians have an unsophisticated interpretation of the Bible, particularly Genesis chapter 1, that leads them into conflict with the evidence of science. It is important to realise that this conflict is the result of faulty understanding rather than something fundamental to Christian belief. These people are usually called creationists and attack the evidence of biology that life developed by evolutionary processes and also in Astronomy (or maybe Cosmology) that the Earth and Universe are billions of years old.

This conflict is not inevitable as people with a sophisticated view of the claims of the Bible see no conflict with science.

Creationists are most strong in the US (they are much more weak in Australia) but for legal reasons have morphed to Intelligent Design (ID)to attempt to hide their religious motivation.

One of the arguments of ID proponents is that some parts of living organisms are so complex that they could not have developed by evolutionary means. Evolution, of cause, is blind, it does not know where organisms (or parts of organisms) will develop in the future. ID proponents claim that therefore evolution cannot work as the individual parts of an organism (or part of an organism) could not work on their own.

Evolutionary theorists have been aware of this issue for many years and have a straight forward answer: complex structures are developed from simpler ones, that had a purpose and function. The function of the individual sections did not necessarily relate to the final function of the large structure. It is one thing to propose this solution to the problem it is another to prove it, but scientists have demonstrated this fundamental idea in many areas.

One of the major arguments of ID is that the bacterial flagellum is so complex ("irreducably complex") that it could not have developed by evolutionary means. This claim has in the last decade been demonstrated to be incorrect.

The video below explains the issue more clearly than I could, and demonstrates that complex structures can develop from simpler ones.



The video above is just part of a talk. Here is the first section of the talk preceeding the video above:




Here is the second section:



Here are a couple of links to articles on this topic:
Panda's Thumb
Rough Guide to Evolution

Creationism and Intelligent Design are wrong on two counts: they are bad theology and bad science