September 01, 2009
Genes Found Unique To Humans
3 genes have been identified that appear unique to humans and we might have a total of 18 genes unique to us.
In this work, David Knowles and Aoife McLysaght of the Smurfit Institute of Genetics at Trinity College Dublin undertook the painstaking task of finding protein-coding genes in the human genome that are absent from the chimp genome. Once they had performed a rigorous search and systematically ruled out false results, their list of candidate genes was trimmed down to just three. Then came the next challenge. "We needed to demonstrate that the DNA in human is really active as a gene," said McLysaght.
The authors gathered evidence from other studies that these three genes are actively transcribed and translated into proteins, but furthermore, they needed to show that the corresponding DNA sequences in other primates are inactive. They found that these DNA sequences in several species of apes and monkeys contained differences that would likely disable a protein-coding gene, suggesting that these genes were inactive in the ancestral primate.
The authors also note that because of the strict set of filters employed, only about 20% of human genes were amenable to analysis. Therefore they estimate there may be approximately 18 human-specific genes that have arisen from non-coding DNA during human evolution.
One wonders whether these regions became active with an initial benefit or did the functional value of the translated regions come later?
These results may seem far-fetched. But a mutation that would cause a previously unused part of the genome to start getting translated into protein might happen in an area which originally came from a viral infection. A portion of viral DNA might have been incorporated into the genome. Also, many more inactive areas of the genome have gotten mutated into activity that caused no benefit or even harm. These few regions that went on to become useful genes arose out of a background of a much larger number of mutations that didn't produce anything useful.
Once we start genetically engineering ourselves the initial changes will involve adding sequences that some people already have. For example, women will want to genetically engineer their melanocytes to produce red or blond hair for example. Also, some men will get genetic engineering for more muscle. These will involve existing genetic sequences already present in the human population.
When things will get really interesting: A much deeper understanding of the functional purposes of genes from other species will turn up many features we do not have that some people will want for themselves or their offspring. When the first genetic transplant from another species into humans is done what will it be done for?
this was covered in 'dark angel'. sensory stuff like night/infravision, echolocation. health stuff like anticancer (sharks), multiple redundancy organs. climate adaptations to tundra or deserts. aqualung.
I totally agree - allthough minor cosmetic changes may beat it a little to the punch - the main intial interest will be in sensory changes/additions.
Of course when we really understand the genome - and how to effectively engineer it - the era of the "natural" organism will be approaching an end and the reign of the "synthetic" organism will truly begin!
Although I am a religious man I do not fear the awesome potential of these technologies - we simply have to be judicious in their use - and that will require a much more rigorous social heirarchy then we currently see among men.
Hero, just a quick FYI, sharks do get cancer.
"Shark cartilage extracts have been touted as treatment for cancer, arthritis and aging because of the claim sharks do not get cancer. But new research demonstrating that sharks do get cancer was presented recently at the 91st annual meeting of the American Association for Cancer Research (AACR).
Researchers at George Washington University Medical Center in Washington, D.C., reported they have documented more than 40 cancerous and benign tumors in sharks and their close marine relatives, including skates and rays. Three of the tumors were chondromas – tumors of cartilage – in sharks."
There's an intermediate step you missed: "reactivating" genes our ancestors used to have.
For example, we have genes for a lot of scent receptors, where the human version of the gene has a stop codon in the middle (making it non-functional), and other animals don't have the stop codon. So we could get a better sense of smell by replacing the spurious stop codons with an appropriate amino acid.
What would that do? Don't know, so we'll do it in a chimp, first.
As for "what makes us human?" I think that's going to be found more in genes like FOXP2, where we have mutations that no other species has, rather than in completely new genes.
I'm admittedly not up to date on the technology so this might be an ignorant question:
Is the subject of designer genes mainly of interest for designing our children or is there, at least theoretically, a way to modify all or most of the genes in our existing bodies? I've seen science fiction stuff about this, but they have warp drives too so that is not a realistic guide.
I'm more interested in the gene from sharks that makes them not have to pay taxes. Give me THAT one.
Doug, the answer to your question is that the interest is purely speculative, because no one knows of an effective way to modify genes nor is there a clear idea of how to accomplish successful modifications. The human genome project was sold as holding the answers to all sorts of questions about disease and life expectancy and evolution etc. The result was few answers and lots of questions. Sure we learned loads, but the biggest thing we learned was that we really didn't know much. Following he completion of the human genome project the science of proteomics exploded. It became clear that DNA did not hold the key to unlocking why we were what we are. It's understanding the DNA and interaction with cellular protein assembly and function that comprise the next step. Will that hold all the answers? Probably not, but we will be one step closer.
When I finished with college etc I wanted to go into transfusion medicine. 21 years ago everyone asked me: 'Why do you want to do that? In a couple of years they will have a blood substitute and you'll be out of a job." 21 years later most companies have given up that quest. Baxter international spent over $1B on R&D and failed. We can't even replicate the oxygen carrying function of red blood cells effectively, much less their other functions.
It's not that we don't know the answers to the questions. We don't even know what to ask yet. The research is important. Without it we will never get the answers much less learn to ask the right questions. The notion that we are close to creating custom genes that will avoid disease or prolong life or give people greater abilities is foolish. We are not even close. We can potentially correct certain specific errors in a very narrow range of cases. That's all.
Eighty years ago the 'science' of eugenics was created with the notion that we knew enough about humanity that we could make a better human. Frankly we have not progressed in our knowledge much more that understanding how such ideas can be misused. It's like a model T and a modern Ferrari. The don't look the same or perform the same, but the difference under the hood is really not that dramatic. We've come a long way in our understanding of genetics. We flatter ourselves to think that we've gone further than we really have on our understanding.
When they refer to "genes" often they are talking about protein encoding genes. However that is a small part of the total. Much of the genes are controls that are essentially computer code that controls the expression of the other genes (both protein encoding and other non-protein encoding). Talking about only the protein encoding genes is like expecting World of Warcraft to be the same as MS Excel just because they both run on the same computer chip.
You could probably revert all 18 of those gene and still have a recognizable human. It's how the proteins are put together not which that matters the most.
An interesting movie in the 30s about a multi millionaire who sought eternal life... He hired a researcher who found documentary records of an English lord who fathered a child at age 95, and lived for 300 years, on a diet of carp guts. They went to his castle and found the lord still alive, but an adult chimpanzee.
The point is many of our genes retain juvenile traits that are lost in the adult chimpanzee.
Some people with genetic defects are already getting tissue and organ transplants to compensate. Look at the parents who've used in vitro fertilization with genetic screening to create a baby to donate immune or other stem cells to an already existing baby they have. This has been controversial. But noone has stopped parents from doing this. So the idea of upgrading people with genetic material effectively is already happening.
Or look at people who go gray. Once they are gray and their melanocytes are no longer producing hair coloring and the tech becomes available to create replacement melanocytes I'm expecting a lot of women to opt for blond coloring even if they were not originally blond.
It is naive in the extreme (sorry, but there is no other way to put it) to suppose that genes are totally independent of each other. There are a gazillion pairs of genes that are unique to humans, not to mention larger groupings. It should be blindingly obvious that something makes us uniquely human, and that the differences between humans and other primates is astronomical in size. I'm quite willing to accept (as a hypothesis) the notion that genetic structure is all-important when it comes to species differentiation, and I would assume that any scientist worth his salt understands that genes (i.e. individual fragments of DNA) do not operate in isolation.
Is is more likely that a mutation would activate a gene or deactivate it?
A tail! I want a tail! w/nice fur, of course, not pubic hair. And definitely prehensile; holding a drink at parties is only the start. One would need to be careful around car doors, though.
Fur would be another cool one. People get tattoos and such. How about a leopard pelt? tiger stripes? Scales, maybe?
Could something be done to lengthen toes so they are more like fingers? Seems reasonable.
Let's start with the tail and see how that works out.