Late last month, fishermen in Japan netted a surprise -- a bottlenose dolphin with two well-developed rear flippers. The flippers are remnants of the legs which grew in the dolphin's prehistoric ancestors.
Every animal's body is built by the genes contained in its DNA. But not all genes are active -- they have to be turned on by controller genes.
Over time, the DNA in a species changes -- new genes emerge, old ones become inactive. But in many cases, the old ones don't completely go away. The controller changes and stops activating the gene. But if there's a change in the controller, it may activate that forgotten gene again.
(The same thing happens with humans. As a baby develops inside its mother, it grows gills and a tail -- remnants of our animal heritage. These disappear before the baby is born.)
Genetic testing is allowing us to determine more and more information about the health and characteristics of our babies while they are still in their mothers' wombs. With this heightened level of awareness and power, we have to ask ourselves some pretty tough ethical questions:
I attended an interesting film and discussion at the Bell Museum last week that focused on many of these issues.
Who's Afraid of Designer Babies? is a documentary mostly following several Australian families grappling with a wide array of genetic issues, from crippling genetic illnesses in their children to more frivolous interest in selecting the sex of their children.
While the discussion was very intelligent and not overly polarized I can say that we were far from a consensus on many of these issues. These are complex issues that we will have to keep hashing out as the technology and social mores change. Haven't formed an opinion yet? Read below for more information.
Genetic Testing & Screening at the University of Minnesota's Center for Bioethics - This is a great resource on the basic questions of ethics that come up around genetic testing.
Genetics and Public Policy Center - "The Genetics and Public Policy Center is a source of accurate and trusted information about public policy related to human genetic technologies and is supported at the Berman Bioethics Institute of Johns Hopkins University by The Pew Charitable Trusts." This group does allot of work in assessing public opinion on these issues.
The US President's Council on Bioethics - This group advises the president on the science and ethical issues behind policy and regulation of biological activities. In the recent past this group has taken a more conservative focus, with President Bush firing several of the more liberal members of the group who actively criticized his position on Stem-cells.
New genetic studies theorize that humans and chimpanzees may have split genetically much later in their evolution than previously thought - as recent as 6.3 million years ago - and that the initial split was followed by phases of interbreeding and hybridization before the two species headed off on their own evolutionary paths.
The results come out of a long and arduous examination of genetic codes of humans, chimps, gorillas and other apes.
“We found that the population structure that existed around the time of human-chimpanzee speciation was unlike any modern ape population,” said David Reich, of the Broad Institute of Harvard and the Massachusetts Institute of Technology. “Something very unusual happened at the time of speciation.”
If the theory is correct, it would mean that present-day humans descended from a chimp-human hybrid, an idea that goes against the current view that hybrid branches tend to lead to dead ends.
The findings, which appeared in the journal Nature, also suggest that some of the oldest “proto-human” fossils may not be human ancestors at all, but may have come from the branch of non-hybrids that died out.
By tracing the history of the X chromosome, scientists determined that after the initial split, females of each species could have bred successfully with males of the other, thereby creating hybrids. Male offspring of this union would probably been sterile, but female offspring would be fertile and could have continued to breed with fertile males of either species, thus creating further hybridization.
Scientists were able to trace the evolutionary history of the X chromosome by comparing human and chimpanzee genes. The genetic evolutionary clock indicated that the male X chromosome found in present day humans wasn’t as old as it should have been had it been passed down from ancestors that came before the initial human-chimpanzee split.
Stories of chimp-human hybrids have been around for centuries, but never confirmed. One recent example from the 1970’s was a performing chimp named Oliver, who was long-rumored to be the product of human and chimpanzee interbreeding. However, DNA studies done at the University of Chicago proved him to be pure chimpanzee.
I am all over this idea. While I don’t personally mind mowing, I know lots of people do, and truthfully, while I don’t mind, I sure would like the additional free time!
In a paper in the May 4 issue of Nature, scientists from the Howard Hughes Medical Institute report that they have figured out a class of hormones that regulates growth in plants – including grass! And while this would be great for me, there are a lot of other good things that could come of this besides a mow-free yard, such as the development of trees that could be halted at a specific height so that they don’t interfere with power lines, raspberry bushes grown taller so that they are easier to pick, and increase the yields of crops such as corn or soybeans.
The key hormones are called brassinosteroids. With this new knowledge regarding brassinosteroids scientists may be able to stop growth in yard grass by limiting brassinosteroids or increase the yield of a crop by increasing brassinosteroids. Increasing crop yields would be very useful, especially considering urban expansion and the loss of farmland worldwide and steadily increasing global populations.
I can’t wait until the mow-free lawn becomes a product – but we’re likely many years away from that happening. Until then, I’ll keep mowing – or just replace my lawn with Field Turf.
Studying genome sequences helps scientists understand how genes work together to direct the growth and health of an organism. Considering the cost and time involved - the dog sequencing took over two years and over $30 million to complete - making the right choices about what species to sequence is an important question. Researchers at the EMBL-European Bioinformatics Institute are proposing a system to determine what organisms should be sequenced next.