Image: Illustration by Brown Bird Design
In Brief
- Scientists thought that among backboned animals, internal fertilization arose 350 million years ago in the group that includes sharks and their kin.
- But new fossil discoveries indicate that copulation—and the carrying of the offspring in the mother’s body until birth—debuted millions of years earlier and in a more primitive group of fish.
- These findings are casting new light on the origin of our own reproductive organs and other body parts.
On a hot August day in 2005 my team and I were out hunting for fish fossils in the tall, grassy paddocks of Gogo Station, a vast cattle ranch located in the heart of northwestern Australia. Today the arid region is hardly suitable for aquatic creatures. But some 375 million years ago, during the Late Devonian period, a shallow sea covered the area and Gogo was home to an enormous tropical reef that teemed with marine life, including a plethora of primitive fishes. Luckily, many of their remains have survived across the ages. Nestled among the clumps of spiky Spinifex bushes and sleepy death adders lie softball-size nodules of limestone—the products of millions of years of erosion of the local shales—some of which harbor pristine fossils of the fishes that lived on the primeval reef. And so over the course of our terrestrial fishing expedition, we would spend our days cracking the nodules open, one after another, hoping to glimpse a treasure inside.
The most abundant of the fishes that patrolled the Gogo reef were armored creatures called placoderms (“plated skin”)—some of the first backboned animals with jaws. Though gone today, placoderms ruled the planet for nearly 70 million years, making them the most successful vertebrate group of their time. Scientists have long debated exactly how they are related to other backboned creatures, and we had come to Gogo to look for specimens that might help resolve this and other questions about fish evolution. On this particular day our efforts were rewarded with a nodule containing what appeared to be a fairly complete fish. It did not strike me as especially remarkable in its anatomy, though, just another placoderm fossil to add to our haul and take back to the lab for extraction from its limestone tomb at a later date. Little did I know that this seemingly modest find would upend scientists’ understanding of a very intimate aspect of vertebrate biology—the origin of sexual intercourse and internal fertilization.
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16 Comments
Add CommentInteresting article. However, I find it quite unimaginable that "gender" just sort of popped into existence a long time ago.
Reply | Report Abuse | Link to thisJust think, surely genderless creatures must have pre-existed gendered creatures. But, the very fact that the early genderless creatures survived, for who knows how long, would have precluded any extremely complicated, incremental and COMPLIMENTARY changes that would have been required to develop a gendered existence.
The very law of "survival of the fittest" would strongly tend to eliminate any slight mutations that, in the future, might EVENTUALLY be found to be useful components of hitherto unknown gendered reproduction.
It makes a whole lot more rational sense to believe that all biological creatures were originally designed by a superior intelligent agent.
Not to refute real scientific inquiry about how nature works. It is just sad how much time and effort is wasted dreaming up theories about origins. That is NOT real science of course, because nothing can be replicated. The evidence can only be interpreted and notions can be proposed. Then we sort of vote on what sounds most reasonable to the most people.
The irrelevant question is, "What REALLY happened?"
Seriously? Thought this article was in Scientific American not the Discovery Institute Weekly. I was unaware that any scientific idea must be repeatable.
Reply | Report Abuse | Link to thisNo, gender did not just "pop into existence". The article is more about the orgigin of internal fertilization, "the deed", "doing it" (a process I replicate as often as possible), than the origin of sexual reproduction with gametes, meiosis fertilization.
There are many flatworms that mate through internal fertilization that do not have a gender, they are hermaphrodites. The one that gets stabbed first gets prego.
Tommy Pain
Reply | Report Abuse | Link to thisTo quote you,
"Seriously? Thought this article was in Scientific American not the Discovery Institute Weekly. I was unaware that any scientific idea must be repeatable."
I recommend that you had better improve your awareness of the scientific method. We are not talking about science fiction here. We are talking about what can be demonstrably proven to be actual fact.
For any scientific claim to be accepted as fact, it must be replicated by other teams or individuals before it can be lifted out of the same black hole in which "perpetual motion" finds itself.
The only way that anything can actually be proven is by finding the same results by independent experimentation. I propose that ALL other claims are, either PURE FICTION or, outright lies.
In any case, flat worms are an incredible example of complexity and beauty, are they not? If you do not think so, perhaps you don't know very much about them.
Haven't read the full article yet...but the
Reply | Report Abuse | Link to this"It makes a whole lot more rational sense to believe that all biological creatures were originally designed by a superior intelligent agent."
by quizzical made me respond...so your stance is that no mater how many intermediates are found between one species and another there is a superior intelligence involved in all the decisions...I just don't see the need....
To Wayne:
Reply | Report Abuse | Link to thisCould you list me a few intermediates between phyla?
quizzical...I'd have to differ their DNA. Which ones are you interested in...
Reply | Report Abuse | Link to thishttp://en.wikipedia.org/wiki/Phylum
The idea that there exist a superior being that creates, destroys, or rearranges matter through out the universe is no more rational than ideas of evolution.
Reply | Report Abuse | Link to thisA hypothesis is simply an educated guess, which is different than a lie or pure fiction. The beauty of science is that it will change conclusions as the facts reveal themselves.
To Wayne:
Reply | Report Abuse | Link to thisAny several will do. I'm sure there must be millions of them, according Darwin's notion that many "small, successive variations" can produce all the varieties of plant and animal phyla we see today.
First I never said a supreme designer was impossible. Only, that the concept of a supreme being and its implications is no less mind boggling, or rational than the idea of spontaneous assembly.
Reply | Report Abuse | Link to thisIn fact, during some of the court cases of creationist vs evolutionist over school curriculums, cited lab experiments about the spontaneous assembly of functional flagella from component parts. The evolutionist won.
We know there is at least some evolutionary processes present in biology via direct observation. Extrapolations have been made back to the origins of life, but they are not lies or pure fiction, but improbable probabilities for sure.
The difference between science and religion is that science distinguishes the difference between what is known and what is believed, with an emphasis on expanding knowledge and reducing belief. Religion celebrates and encourages belief without proof, i.e. faith! I wonder what is the probability of stubling across the truth using faith? Zero...
You are right. Don't let me put words in your mouth.
Reply | Report Abuse | Link to thisI just find it rather "unscientific" when so-called scientists present some imaginary notion as if were undisputed fact.
Have a happy New Year!
Are the comments on this article really spiralling into another irrelevant supreme being/intelligence debate? I thought this was scientific american not yahoo.
Reply | Report Abuse | Link to thisThe Adam and Eve story sounds better to me and more believable, and I have degrees in chemical engineering and computer programming. In fact, I think evolutionary theory is damaging science. It's a form of pseudo-science or alchemy that leads to the occult (spiritual pantheistic evolution) and it's a waste of time that could be used for something worthwile like trying to cure the common cold or get gas below $3/gal.
Reply | Report Abuse | Link to thisAs a physicist and clergyman, I'm listening with empathy to both "camps."
Reply | Report Abuse | Link to thisThere is no question that "designers" are, by faith, believing that life forms came into existence because of design by an intelligent being. I asked this question years ago in graduate school of my microbiology professor--he said the design was in the electron shell structure!
It should also be pointed out that it takes "faith," if you will, to accept that the enormous complexity of life evolved in minute base-pair accidental mutations.
For the commenter who seemed to feel there were adequate intermediate organisms to account for these mutations--I'm afraid you are completely fooling yourself. The entire scientific community admits to the great puzzle of: 1. The absence of anything even close to sufficient intermediate forms. 2. And furthermore, the Cambrian Explosion. We never find proto-organisms--the earliest fossil record reveals complex systems at the very start.
I'm a scientist. By definition science does not allow the supernatural. Biblical faith is defined only in the context of the supernatural. So in this sense, supernatural design, by definition, cannot be science. I'm amazed that this is not understood by the apologists from either side. The scientists shouldn't be chastising the ID believers because they are not scientific because they don't have "scientific" evidence--they should be forthright and say, "By definition you have no science."
Conversely, it is blindness for them to claim the ID people don't have evidence for intelligence in the design of living systems. You have to be a fool to argue the incredibly complex systems, which are so dependent on each other for survival, evolved in step-wise fassion. So along come the punctuated equilibrium postulates which deepen the mire because you completely depart from long term evolvement.
Finally, don't forget that the world's preminent evolutionary philosopher, Antony Flew, changed his position and wrote a book, "There Is A God!" because, to use his words, of the profound complexity of living systems. And how can we be so arrogant as to admit anything other than we are yet scratching the surface of this complexity? I realize he is "only" a deist and doesn't believe in the "Judao-Christian" God. But that's not the issue here--he is now in the intelligent design camp.
Finally, for those of you who don't get a chance to read the Bible--the definition of faith is said to be substance and evidence... so that the things which are seen were not made of things which do appear. Hebrews 11:3
As a physicist and clergyman, I'm listening with empathy to both "camps."
Reply | Report Abuse | Link to thisThere is no question that "designers" are, by faith, believing that life forms came into existence because of design by an intelligent being. I asked this question years ago in graduate school of my microbiology professor--he said the design was in the electron shell structure!
It should also be pointed out that it takes "faith," if you will, to accept that the enormous complexity of life evolved in minute base-pair accidental mutations.
For the commenter who seemed to feel there were adequate intermediate organisms to account for these mutations--I'm afraid you are completely fooling yourself. The entire scientific community admits to the great puzzle of: 1. The absence of anything even close to sufficient intermediate forms. 2. And furthermore, the Cambrian Explosion. We never find proto-organisms--the earliest fossil record reveals complex systems at the very start.
I'm a scientist. By definition science does not allow the supernatural. Biblical faith is defined only in the context of the supernatural. So in this sense, supernatural design, by definition, cannot be science. I'm amazed that this is not understood by the apologists from either side. The scientists shouldn't be chastising the ID believers because they are not scientific because they don't have "scientific" evidence--they should be forthright and say, "By definition you have no science."
Conversely, it is blindness for them to claim the ID people don't have evidence for intelligence in the design of living systems. You have to be a fool to argue the incredibly complex systems, which are so dependent on each other for survival, evolved in step-wise fassion. So along come the punctuated equilibrium postulates which deepen the mire because you completely depart from long term evolvement.
Finally, don't forget that the world's preminent evolutionary philosopher, Antony Flew, changed his position and wrote a book, "There Is A God!" because, to use his words, of the profound complexity of living systems. And how can we be so arrogant as to admit anything other than we are yet scratching the surface of this complexity? I realize he is "only" a deist and doesn't believe in the "Judao-Christian" God. But that's not the issue here--he is now in the intelligent design camp.
Finally, for those of you who don't get a chance to read the Bible--the definition of faith is said to be substance and evidence... so that the things which are seen were not made of things which do appear. Hebrews 11:3
Why do people fight against evolution so much? Look, it's happened, is happening, and will continue to happen. Only because it contradicts literal interpretations of all creation fables doesn't make it any less true. I don't tolerate idiots, and sadly denying evolution is a form of lunatic idiocy...
Reply | Report Abuse | Link to thishttp://factsnotfantasy.com/evolution.php
That is the point of science: to examine where we came from, what's going on in the world around us, and making predictions about the future. If you have a problem with scientists looking into our origins, then you can stick with your "a wizard/god did it with magic" hypothesis while the rest of try to find out what really happened.
Reply | Report Abuse | Link to this