DNA Reveals Lost Sweet Tooth of Cats

Poor kitties (and other carnivorous mammals). It turns out that evolution has taken away their ability to taste sweets! 

When it comes to the evolution vs. intelligent design debate, there are many studies that have been shown to support the fact that evolution has occurred. 
 
A recent study from the Monell Chemical Senses Center suggests that after humans diverged from our ancestors, many mammals lost some of their tasting ability. In this study, they analyzed DNA from 12 species of carnivorous mammals and found that seven of them had completely nonfunctional versions of the genes that allow us to taste and appreciate sweets. So whenever you try to slip your cat some sweets, don't even bother because they can't even enjoy them!

This is cute. But kitties can't taste sweetness =[

This concept of loss of function in animals was discussed in Darwins Origin of Species. In the book, Darwin talked about loss of vision observed in animals that live in darkness, which is the case in termites. He emphasized that evolution is not a particular strategy for improvement but rather it's more of living animals adapting to survival in their environments, and traits that are no longer necessary can be lost. It makes sense that carnivorous mammals have lost their ability to taste sweets because you don't need to be able to taste sweets when you're not eating plants (sweetness helps distinguish between toxic and nutritious plants).

To the dog-owners reading this, don't fret. Dogs can still taste sweets. But it's probably only a matter of time before evolution knocks that trait out. Until then, companies will continue to pump starch and sweets into their dog foods to keep you, and your dog, coming back for more.

This dog loves his sweets!

So clearly this study supports the fact that evolution has occurred...and so the support for evolution goes on...

Read the article here: Major taste loss in carnivorous mammals

-Rachael Morris

Evidence for Evoluton Case Study: The Simpsons

Evolution is real, according to The Simpsons. Watch Homer evolve from a single-celled organism to a complex human.

 

Happy Watching,

Rachael

Missing Links

The missing link argument is a well-known one. Using the fossil record, evolutionary biologists have shown the development of traits among many organisms. Examples include the ancestors of human, in which the change from quadrupedal to bipedal movement can be seen, and the transition of whales from land animals to ocean dwelling ones, in which the loss of hind limbs can be observed. However, some organisms have remained inexplicable using missing links.

One such group is the flatfishes, which includes halibut and flounder. Flatfishes have both eyes on one side of their head and, when at rest, display only one side of their body. For years, biologists have tried and failed to find any proof that these fish developed their odd eye placement through transition species. The flatfish have been explained through the ‘hopeful monster’ hypothesis, which is the idea that an organism was at random born with a severe but extremely helpful allele that then became common throughout the population.

Supporters of intelligent design have claimed that the hopeful monster is actually the work of God. They argue that God seized the chance to create a better functioning organism, a decision that gave rise to a hopeful monster. Intelligent design believers have pointed to the conspicuous lack of fossil evidence for many transitional species as proof that organisms are often created by the hand of God, and flatfishes are one of their common examples.

Recently, though, transition fossils have been found for flatfishes. These fossils have eyes on both sides of their heads, but one eye is higher on the head than the other, which evolutionists are arguing is proof that this species was likely undergoing natural selection in favor of both eyes on one side of the head.

Believers in intelligent design often ask why random changes, such as the partial movement of one eye, could possibly be favored in any way. In the case of flatfishes, evolutionists have proposed that once the fish developed their behavior of lying with only one side revealed, even the slight movement of one eye would increase their ability to see and thus increase their fitness.

Despite this fossil find, many creationists still believe that the fish could have been intelligently designed. They do not oppose that organisms are widely varied, but they disagree that any of that variation is due to evolution. As far as the flatfishes are concerned, creationists appear content to accept this new fossil as a slight variant of the fish found now. In no way do they think it proves that the fish evolved.

And so, the debate between evolutionists and creationists rages on.

~Katelyn Larson

(Here's the link to the article I found this information in, if you're interested: http://news.nationalgeographic.com/news/2008/07/080709-evolution-fish_2.html)

OBSESSED WITH SEX? IT'S ONLY EVOLUTION!

The Evolution of Sex

Do you remember the night you went to sleep as a child and were rudely awakened in the middle of puberty? Amidst the inexorable changes Nature was forcing on your body, there was something flooding your body, making you rebellious and moody. Yes, the uncontrollable adolescent hormones were wrecking havoc with your psyche, and the most important change they made was to make you more aware of the one thing that all parents dread having to talk about – sex.

If we are to look at evolution with a single-minded point of view, and ask the question “What is the purpose of evolution?”, the answer is stark. Reproduction. From a Darwinian point of view, sex is more important than life itself. But why is it such a big deal? Why is it so important, and what is all the hullabaloo about?

At first glance, sex seems extremely cumbersome to be bothered with. There is the stress of having to find a mate, and it can be extremely time-consuming and exhausting. But A recent study by National Geographic Magazine found the reason for the hype (or at least one of them!). Sex has been found to lead to faster evolution. Using yeast as model organisms, this research proved without a doubt, that in times of stress, organisms that can reproduce sexually have a definite advantage over those who reproduce clonally. Why this happens is still unclear, though genetic variation has been cited the top contender for this debate.

PBS Houston has an incredible series on Evolution, and this is the preview to the episode themed “Why Sex?”

Today, two main theories remain as to why sexual reproduction is more advantageous than asexual reproduction, and why it exists at all.

 

First, the deleterious mutation hypothesis, proposed by Alexey Kondrashov, was the idea that sex exists to purge a species of damaging genetic mutations. The second was the Red Queen Hypothesis, proposed by Leigh Van Valen of the University of Chicago. The hypothesis is simple: sex is needed to fend off disease and keep healthy.

These questions lead to further, even more interesting, social ones. One that has been widely asked is if love is an evolutionary tactic as well. There has not been, and perhaps cannot be any research on the matter. In the same PBS series that I have mentioned above, here is an excerpt on the subject:

“Ask any peahen what she wants in a mate, and you're likely to get the same answer: eye-popping, elegant plumage. A peacock not equipped with a set of big, provocative tail feathers is doomed to a frustrating sex life. Peahens always pick well-endowed suitors over drab ones, and biologists see the evolutionary logic behind it -- healthy birds, with showy feathers, are likely to father healthy offspring.

But ask any person what she or he wants in a mate, and the range of answers is bewildering. "A kind heart." "Great legs." "Someone who loves kayaking." Yet some scientists in a field called evolutionary psychology propose that we all share instinctive preferences, and that what we humans find alluring in a mate is rooted in our evolutionary past.”

What are your thoughts on the this debate? I would like to end today’s session leaving you with this:

6 Arguments Against Evolution

I found an article in National Geographic that sums up 6 different arguments that proponents of intelligent design have against evidence for evolution, and I thought I’d summarize that article here.

http://news.nationalgeographic.com/news/2009/11/photogalleries/091123-origin-species-darwin-150-intelligent-design/index.html

1. The Eyes of Vertebrates

Arguments for Intelligent Design (ID):

An argument for ID regarding vertebrate eyes is that they say that these eyes could not have evolved gradually, in a stepwise fashion, because every component of the eye is needed for it to work. They say that you would need the retina, lens, cornea, and other important parts of the eye all at once, which is indicative of some “intelligent designer”.

Arguments for Evolution:

There have already been several evolutionary schemes that show that the eye could indeed have evolved in a stepwise fashion, from a simple photoreceptor spot to the modern human eye.

(on a side note, those of us who took EBIO 202, which I think is everyone in this class, would have already seen this example of a stepwise evolutionary scheme for the eye)

2. The Cambrian Explosion

Arguments for ID:

The abrupt explosion in biodiversity during the Cambrian Explosion would require huge amount of information to be “injected” into the biosphere rapidly, which only an intelligent designer could do. Because evolution is reliant on the occurrence of chance mutations to drive evolution forward, it is unlikely that the gradual introduction of information into the biosphere from mutations would be sufficient to cause the Cambrian explosion.

Arguments for Evolution:

The Cambrian Explosion was not actually very abrupt, as it took place over the course of several million years and fossil discoveries indicate that there were complex organisms prior to the Cambrian explosion.

3. DNA

Arguments for ID:

Because DNA codes all the information needed for life, it can be said to have a high degree of what is known as CSI (or complex specified information). The only other systems on Earth with high CSI are man-made, such as machines or language, which were created by humans. So you need intelligence to creates a system with high CSI.

Arguments for Evolution:

Once DNA was formed through chance events in primordial earth, natural selection could take over to drive DNA to code for increasingly complex molecules over an incredibly large span of time.

4. Bacterial “Legs”

Arguments for ID:

This is basically the same argument as for the vertebrate eyes. Flagella are very complex, and the absence of any one of its parts would cause it to stop working, making it unlikely for them to have evolved gradually.

Arguments for Evolution:

Several intermediate steps have been discovered leading up to the bacterial flagellum.

5. Whales

Arguments for ID:

Whales have a long generation time, and they have small populations, so they’re essentially a worst-case scenario for evolving rapidly, which makes it mathematically unlikely for them to have transitioned from terrestrial mammals to aquatic mammals over the last ten million years.

Arguments for Evolution:

There is evidence in the fossil record of archaic whales that were initially terrestrial but become more aquatic over time. Again, 50 million years is an incredible span of time.

6. “Universal Perfection”

Arguments for ID:

We inhabit a universe that is remarkably well suited for life to occur, from the precise distance of Earth to the Sun, to the value of the gravitational constant. The value of the gravitational constant is extremely important because it is just right for creating planets orbiting stars with lifetimes long enough for life to evolve. This supports the existence of a supernatural entity that designed the universe with life in mind.

Arguments for Evolution:

Something about there being multiple universes. In my completely biased opinion, I’ve always thought that was abstract nonsense, but it’s their argument for why our universe is as hospitable to the development of life as it is.

We Found the Hominids But Where Are the Chimpanids?

In searching to better understand the intelligent design/evolution debate I’ve come across many different arguments – all making good points as well as making questionable ones. I was having a hard time deciding exactly what to focus on.While immersing myself in this debate I've also been researching for another project dealing with Neanderthals – precursors to humans (or so the evolution theorists say). In researching these hominids and other proto-humans I thought what of chimpanzees? do they, too, have proto-chimpanzees – (chimpanids I’ll call them)?

According to evolutionary biologists, at one moment in time there existed a common ancestor of the chimpanzee and the modern human. After a long period of time a split formed – proto-human going its way and proto-chimpanzee going its way (5 to 8 million years ago). So far scientists have discovered skeletal remains of hominids leading up to the modern human but what of chimpanids leading up to the modern chimp?

Here I had finally found a question I had never considered!

I began searching then for any information on the evolutionary development of the modern chimpanzee – surely they have a similar amount of fossils to that of the hominid fossils, or at least a couple suggesting a gradual change from common ancestor to modern chimp.

In searching I found an article about such fossils. The find happened in 2005 (6 years ago); and the discovery? Teeth. 500,000 year-old teeth are the first known chimpanzee fossils.

It is impossible to tell if these teeth belong to modern chimpanzees or some proto-chimpanzee – a species long extinct. If it is the case that those teeth belong to a modern chimpanzee, then these chimps have been around quite a long time. The modern human has been around for only 200,000 years while an ancestor of the modern human, Homo erectus, had lasted about 1 million years.

http://a57.foxnews.com/images/324851/450/350/0_21_071112_nakayamai.jpg

With this find another question emerged: did the human-chimp separation happen do to physical separation as previously believed?

Prior to this discovery the main theory suggested that “chimps never crossed east of the Rift Valley, but instead stayed in the jungles of western and central Africa.”  However the chimp remains found were east of this divide. This discovery not only calls into question the cause of separation between humans and chimps evolutionarily but it also undermines the theory of how humans evolved bipedalism – the previous claim being that because proto-humans lived in a savannah bipedalism was a necessary adaption; Yet here scientists have found chimps living in these semi-arid conditions as well.

So what does all this have to do with the intelligent design/ evolutionary debate? I suppose it is another unanswered question in the evolutionary theory. Intelligent design can explain this problem by simply stating there was no divide to begin with. There were separate species already made – unrelated to one another except for the “fact” that they came from a designer. There was no proto-chimp or proto-human – just different species of non-human. Then, an intelligent designer created the first humans. There was no gradual change of one species of hominids into Homo sapiens. All of this of course is speculation as there is no evidence of this intelligent designer like there is the fossil record for evolution (although one could argue the fossil record has little evidence of gradual change).

http://media.photobucket.com/image/recent/roadrunner_876/rt_jaw_bone_071113_ms.jpg 

Another issue I’m having that is not addressed in the article is the identification of the fossils found. The paleontologists found three 500,000 year old teeth – three! Apparently this is enough to say what species they belong to. That alone is amazing to me but I must say questionable too. The anthropologist behind the find, Sally McBrearty, says that the lack of chimpanzee fossils is a “frustrating puzzle” but easily explainable – fossils are rare and the supposed habitat of these chimpanids is not conducive to fossilizing bones. A nice tidy answer to the big problem in the evidential value of the  fossil record but that is for another blog entry.

Nonetheless, it is a fascinating discovery that seemed to have gotten swept under the rug (well I hadn’t heard of this discovery before). McBrearty says in the article that she will return to the area of the discovery to look for more chimpanzee fossils. No one was expecting to find chimpanzee fossils in the hominid habitat but now there is new perspective. Hopefully with these fresh eyes more will turn up – perhaps a couple of phalanges or some rib bones.

--Elise Edoka

news article: http://www.nature.com/news/2005/050831/full/news050829-10.html