Posted on 02/08/2005 3:50:43 AM PST by PatrickHenry
A group of four-footed mammals that flourished worldwide for 40 million years and then died out in the ice ages is the missing link between the whale and its not-so-obvious nearest relative, the hippopotamus.
The conclusion by University of California, Berkeley, post-doctoral fellow Jean-Renaud Boisserie and his French colleagues finally puts to rest the long-standing notion that the hippo is actually related to the pig or to its close relative, the South American peccary. In doing so, the finding reconciles the fossil record with the 20-year-old claim that molecular evidence points to the whale as the closest relative of the hippo.
"The problem with hippos is, if you look at the general shape of the animal it could be related to horses, as the ancient Greeks thought, or pigs, as modern scientists thought, while molecular phylogeny shows a close relationship with whales," said Boisserie. "But cetaceans – whales, porpoises and dolphins – don't look anything like hippos. There is a 40-million-year gap between fossils of early cetaceans and early hippos."
In a paper appearing this week in the Online Early Edition of the Proceedings of the National Academy of Sciences, Boisserie and colleagues Michel Brunet and Fabrice Lihoreau fill in this gap by proposing that whales and hippos had a common water-loving ancestor 50 to 60 million years ago that evolved and split into two groups: the early cetaceans, which eventually spurned land altogether and became totally aquatic; and a large and diverse group of four-legged beasts called anthracotheres. The pig-like anthracotheres, which blossomed over a 40-million-year period into at least 37 distinct genera on all continents except Oceania and South America, died out less than 2 and a half million years ago, leaving only one descendent: the hippopotamus.
This proposal places whales squarely within the large group of cloven-hoofed mammals (even-toed ungulates) known collectively as the Artiodactyla – the group that includes cows, pigs, sheep, antelopes, camels, giraffes and most of the large land animals. Rather than separating whales from the rest of the mammals, the new study supports a 1997 proposal to place the legless whales and dolphins together with the cloven-hoofed mammals in a group named Cetartiodactyla.
"Our study shows that these groups are not as unrelated as thought by morphologists," Boisserie said, referring to scientists who classify organisms based on their physical characteristics or morphology. "Cetaceans are artiodactyls, but very derived artiodactyls."
The origin of hippos has been debated vociferously for nearly 200 years, ever since the animals were rediscovered by pioneering French paleontologist Georges Cuvier and others. Their conclusion that hippos are closely related to pigs and peccaries was based primarily on their interpretation of the ridges on the molars of these species, Boisserie said.
"In this particular case, you can't really rely on the dentition, however," Boisserie said. "Teeth are the best preserved and most numerous fossils, and analysis of teeth is very important in paleontology, but they are subject to lots of environmental processes and can quickly adapt to the outside world. So, most characteristics are not dependable indications of relationships between major groups of mammals. Teeth are not as reliable as people thought."
As scientists found more fossils of early hippos and anthracotheres, a competing hypothesis roiled the waters: that hippos are descendents of the anthracotheres.
All this was thrown into disarray in 1985 when UC Berkeley's Vincent Sarich, a pioneer of the field of molecular evolution and now a professor emeritus of anthropology, analyzed blood proteins and saw a close relationship between hippos and whales. A subsequent analysis of mitochondrial, nuclear and ribosomal DNA only solidified this relationship.
Though most biologists now agree that whales and hippos are first cousins, they continue to clash over how whales and hippos are related, and where they belong within the even-toed ungulates, the artiodactyls. A major roadblock to linking whales with hippos was the lack of any fossils that appeared intermediate between the two. In fact, it was a bit embarrassing for paleontologists because the claimed link between the two would mean that one of the major radiations of mammals – the one that led to cetaceans, which represent the most successful re-adaptation to life in water – had an origin deeply nested within the artiodactyls, and that morphologists had failed to recognize it.
This new analysis finally brings the fossil evidence into accord with the molecular data, showing that whales and hippos indeed are one another's closest relatives.
"This work provides another important step for the reconciliation between molecular- and morphology-based phylogenies, and indicates new tracks for research on emergence of cetaceans," Boisserie said.
Boisserie became a hippo specialist while digging with Brunet for early human ancestors in the African republic of Chad. Most hominid fossils earlier than about 2 million years ago are found in association with hippo fossils, implying that they lived in the same biotopes and that hippos later became a source of food for our distant ancestors. Hippos first developed in Africa 16 million years ago and exploded in number around 8 million years ago, Boisserie said.
Now a post-doctoral fellow in the Human Evolution Research Center run by integrative biology professor Tim White at UC Berkeley, Boisserie decided to attempt a resolution of the conflict between the molecular data and the fossil record. New whale fossils discovered in Pakistan in 2001, some of which have limb characteristics similar to artiodactyls, drew a more certain link between whales and artiodactyls. Boisserie and his colleagues conducted a phylogenetic analysis of new and previous hippo, whale and anthracothere fossils and were able to argue persuasively that anthracotheres are the missing link between hippos and cetaceans.
While the common ancestor of cetaceans and anthracotheres probably wasn't fully aquatic, it likely lived around water, he said. And while many anthracotheres appear to have been adapted to life in water, all of the youngest fossils of anthracotheres, hippos and cetaceans are aquatic or semi-aquatic.
"Our study is the most complete to date, including lots of different taxa and a lot of new characteristics," Boisserie said. "Our results are very robust and a good alternative to our findings is still to be formulated."
Brunet is associated with the Laboratoire de Géobiologie, Biochronologie et Paléontologie Humaine at the Université de Poitiers and with the Collège de France in Paris. Lihoreau is a post-doctoral fellow in the Département de Paléontologie of the Université de N'Djaména in Chad.
The work was supported in part by the Mission Paléoanthropologique Franco-Tchadienne, which is co-directed by Brunet and Patrick Vignaud of the Université de Poitiers, and in part by funds to Boisserie from the Fondation Fyssen, the French Ministère des Affaires Etrangères and the National Science Foundation's Revealing Hominid Origins Initiative, which is co-directed by Tim White and Clark Howell of UC Berkeley.
The Origin of Species tells us that life evolves. It has nothing to do with creation of life.
So, you are bringing in the same stupid strawman that creationists have been lying about for years. Give us a break and learn some biology.
Correct. They are not. They are laws. That is, descriptions or models of how some (idealized and representative) physical system behaves.
Yet they all started as postulates and were proven mathematically.
Pardon? How were they "proven mathematically"? Sure, they're formulated mathematically. They, or elements of them, are expressed in the language of some mathematical system. But this is nothing at all like saying they are "proven mathematically".
If something is "proven mathematically" that means you could, in principle, sit down with a piece of paper, or at a computer, and determine it's validity purely by calculation and formal analysis without respect to what happens or doesn't happen in the natural world. That's crazy because what happens, or doesn't, in the natural world is precisely what these laws are all about!
You are -- in effect -- saying that you can evaluate (even "prove"!) a law of nature without the necessary step of examining nature!!! (Relating a formalism like a scientific law to real instances in nature will necessarily involve some, indeed many, non-mathematical assumptions and inferences. Not to mention that it is never close to possible to test all possible real instances in which the law should apply, which would be the minimum necessary to literally prove it.)
Yeah, if you don't believe bronze aged silliness, you will go to H E double hockey sticks. This is exactly the silliness that conflating the Good News of Christ's resurrection with Genesis causes.
That statement is proved false quite easily.
RECENT CREATION
In his gospel, Luke, the beloved physician, recorded 75 generations from Jesus to Adam.26 Using the numbers found in the Old Testament, Theophilus and others 27 added up the number of years from the creation of the world. Theophilus concluded,
There are not two myriads of myriads (28) of years, even though Plato said such a period had elapsed between the deluge and his own time, . . . The world is not uncreated not is there spontaneous production of everything, as Pythagoras and the others have babbled; instead the world is created and is providentially governed by the God who made everything. And the whole period of time and the years can be demonstrated to those who wish to learn the truth. . . . The total number of years from the creation of the world is 5,695.29
Regarding the total number of years, Theophilus acknowledged,
If some period has escaped our notice, says 50 or 100 or even 200 years, at any rate it is not myriads, or thousands of years as it was for Plato . . . and the rest of those who wrote falsehoods. It may be that we do not know the exact total of all the years simply because the additional months and days are not recorded in the sacred books."30
Origen (b. 185), the great theologian of the Greek churches, defended "the Mosaic account of the creation, which teaches that the world is not yet ten thousand years old, but very much under that."31
And Augustine (b. 354), the great bishop of the Latin churches, wrote, "the Scripture . . . has paramount authority, . . . to which we yield assent in all matters."32 "That God made the world, we can believe from no one more safely than from God Himself."33
On the age of man and the earth, Augustine wrote, Some hold the same opinion regarding men that they hold regarding the world itself, that they have always been . . . . And when they are asked, how, . . . they reply that most, if not all lands, were so desolated at intervals by fire and flood, that men were greatly reduced in numbers, and . . . thus there was at intervals a new beginning made. . . . But they say what they think, not what they know. They are deceived . . . by those highly mendacious documents which profess to give the history of many thousand years, though reckoning by the sacred writings, we find that not 6,000 years have yet passed.34
Care to recent?? You stated that it is only a RECENT thing to believe in a young eqarth...
See? All you have to do is Believe what the Bibel says, and it all falls into place.
The following is a partial list of people who were both scientists and creationists. Note that the "founder" of the scientific method was a creation science adherent. Both of you tell me with a straight face that these scientists are "quacks" and non-scientists.
Early
The Age of Newton
Just Before Darwin
Just After Darwin
The Modern Period
"I said simpler creature because it seems to me that if you're 'evolving' you're taking a step up from something less."
Is a tapeworm simpler than a free-living flat worm?
It doesn't matter what "seems" to you. It matters what the science is. Evolution goes in the direction of survival of populations not complexity.
Shubi just wrote that God is stupid. That sounds to me like hatred toward God.
If you don't know either, just say so.
Good analysis, but hardly a theory. ;-)
You have the audacity to imply that I am lying like Kerry did?
Your fervor in defending evolution is beyond "religious".The arrogance of your postings insulting all who ask questions is disgusting and is far from convincing anyone of the validity of your opinion.
Nothing more to say.
When sects of Christianity spout nonsense they drive people that know better away from Christ. This is the problem with the heresy that is creationism. It rejects science and embraces misinterpretation of the Bible.
This misinterpretation is used to try to convince people that if you don't believe that all the species in the world floated around on a wooden boat for a year you can't believe in Christ. This is nothing more than heresy almost to the point of blaspheming the Holy Spirit. It is attributing things to God that He did not do and by doing so implying that nonsense is Holy Spirit inspired.
Someone can be an engineer and still completely ignorant of biology.
The light is beginning to dawn! Creationism is a cult.
I find the whole "there are no transitional species" argument highly amusing.
going by this rationale, there should be NO record, of any sort, of creatures capable of certain functions BUT NOT PERFECTLY SUITED TO EXECUTE THESE FUNCTIONS WELL.
You and I both know that this is far from the case.
I am grown weary of the Creationist crowd's disingenuousness. They never fail to ignore the arguments their philosophical ancestors have put forth - the ones that have been utterly trounced (eg: there can never have been any extinctions, etc...)
According to their philosophy, all forms of life must have been concurrent. This is not so.
According to them, there can never have been any succession of species (one form appearing at time=a, disappearing at time=g, another form appearing at time=m, disappearing at time=s, etc...). This is not so.
In earlier times, the very notion that species are related was anathema to them. NOW, having had too much proof paraded before their superglued-shut eyes for even them to completely deny it, they now claim to have never claimed species are not related, but that "adaptation does not lead to speciation". Geesh - a casual review of interbreeding patterns of the arctic-ring seagull species blows THAT out of the water, but damn me if I can figure out a way of making them see this.
And they wonder why we seem to be getting fed up with them.
Just a step up in survival, not necessarily complexity or goodness. You have the definition of evolution wrong. This is a severe problem among creationists who argue against evolution. They distort and misuse scientific definitions.
"I've noticed that many people's belief in evolution stems from their hatred toward God...."
Did you notice on my personal page that I have a Dr. in Ministry and direct a homeless ministry in the inner city?
So don't accuse me of hating the guy I work for. ;-)
Are you saying that all those scientists opposed evolution? Most of them died before Darwin lived.
No he didn't. You must be one of those "soldiers of God" that doesn't have to obey the Ten Commandments, specifically that one about bearing false witness (also more commonly known by a simpler term).
So?
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