On science blogs this week: Life on Man
Written by Tabitha M. Powledge Blog
GUT FEELING ABOUT THE HUMAN MICROBIOME. It's not only the biggest science/medical news this week, it's probably the biggest science/medical news this year, or maybe this decade, or possibly even this century. How many times have you heard this claim before: the potential consequences are enormous, and not just for health and disease. This time it's true.
The news is that researchers have begun publishing results of the Human Microbiome Project. The goal is to make a map of Life on Man. Each of us is home to perhaps hundreds of thousands of species of bacteria, fungi, and even algae, and that's not counting the uncountable viruses. I have noted here before that my favorite scifact is this one: 9 out of 10 of your body's cells aren't you at all, they're microbes. This week we stand on the threshold — but only on the threshold — of discovering what this means.
Affe mit Schädel, bronze by Hugo Rheinhold c. 1893
This first take on identifying the microbial populations of normal healthy humans is occupying a score or more of just-published papers, and nearly all of them are free.
If you don't believe me on how significant this is, believe a guy who really knows: the indispensible evolutionary biologist Jonathan Eisen. At Tree of Life, he obliges us with dozens of links — to several individual papers, to a score (or more) of news stories, to a collection of his own posts, to past blog posts of others, to the Human Microbiome Project site, and to a video of his TEDMED talk.
Eisen's link list will keep you busy for weeks. You will not, however, find any papers from Science among them, even though the journal published a section of several microbiome papers in the June 8 issue. Apparently these are not official Human Microbiome Project papers like the ones in Nature and the PLoS journals that Eisen cites. But in Science there are several reviews ("The Application of Ecological Theory Toward an Understanding of the Human Microbiome," "Host-Gut Microbiota Metabolic Interactions" and others), news stories, opinion pieces, etc.
Definitely worth your perusal as well. You were planning to devote your entire summer to studying human microbiology, weren't you?
Science is not, of course, an open-access journal. However, it is making a brief exception to that practice for these microbiome papers. The whole section of a dozen or more items is available free with registration until June 28. Get a wiggle on.
In case you've got other fish to grill this summer, you can check out the Human Microbiology Project Lite. Here are two blog posts for general audiences: Rob Stein at the NPR blog Shots and George Dvorsky at io9.
ON THE SLIPPERY SLOPE TO HUMAN GENETIC ENGINEERING. It hasn't actually been accomplished yet in humans, which is maybe why there hasn't been much blogging about a report from the UK arguing that it's OK to jigger with human eggs to cure mitochondrial diseases.
A mitochondrion. Credit: NIH
As you will have read a thousand times, mitochondria are the cell's power plants. Mitochondria have their own small genomes that have nothing to do with what we usually think of as "the genome," the DNA in the cell nucleus. Mitochondrial genomes also carry mutations that can cause disease, sometimes awful progessive incurable diseases like dementia. Because women bequeath their own mitochondria in their eggs to all their children, they can also pass on any mitochondrial disease.
This week the UK's Nuffield Council on Bioethics issued a long report concluding that nothing much was morally wrong with the idea of removing a mutant mitochondrion from an egg, inserting an unmutated one from another woman, and using the engineered egg for in vitro fertilization.
Here's why this is a much bigger deal than it might seem at first. A new girl baby resulting from this procedure would possess the foreign mitochondrion in her own eggs too, and would pass it to her children. And her daughters would pass it to theirs. Etc. down the generations forever.
Gene therapy procedures that would bequeath manipulated DNA to descendants is a kind of human genetic engineering generally called germline therapy. Germline therapy is also where people have usually wanted to draw a moral line with artificial reproductive procedures. The reasoning has been that, while it's OK to use genetic manipulation to try to cure disease in an individual, it's not OK to mess around with the genes of future generations. The Nuffield folks acknowledged that mitochondrial replacement is a form of germline therapy. Gretchen Vogel has a short explanatory post at ScienceInsider.
In his more detailed piece for the Nature Newsblog, Ewen Callaway quotes the chair of the group producing the report, science journalist Geoff Watts, arguing that swapping mitochondria presents a different set of ethical issues than fiddling with nuclear genes. From the posts I'm not clear on why the issues are different and what the differences might be, but I haven't read the report. Maybe it explains. Callaway noted
Watts sees the debate over the ethics of mitochondrial transfers as a “dry run” for the debate that will eventually occur when gene-editing technologies mature. “It’s obvious that sooner or later someone is going to want to do this in nuclear genes,” he said at the briefing.
THE BONOBO GENOME SEQUENCE IS HERE. NEXT STOP, WORLD PEACE?. On the other hand, if some people's hopes are realized, we should set to work engineering better humans as soon as we find out just which genes incline bonobos, the peaceable sexy ape, to make love, not war. (Let us also note that if we are to achieve the goal of World Peace through genetic engineering, the new genetically improved Homo sap will probably have to be raised in a culture that makes love, not war, just as bonobos are. Which will likely be a lot harder to achieve than genetic manipulation.)
Pan paniscus, aka bonobo. Credit: Pierre Fidenci
However, a first step has been achieved because the Bonobo Genome Project has been completed. For blogging the news see John Timmer at Ars Technica, and Robert Gonzalez at io9, and Ricki Lewis guest-blogging at SciAm
The most significant revelation is that Homo sap is as closedly related to bonobos as we are to the crabby, combative chimpanzees. It's tempting to see our own species as wandering back and forth between the two ways of life exemplified in the genus Pan, now warlike, now pacifist and (as the blog posts keep putting it) promiscuous. Perhaps some would like to genetically engineer Homo sap to pursue peace without promiscuity, but suppose you can't have one without the other? That will be interesting to find out.
There are other potential lessons here too. Bonobo social organization revolves around females, while chimps are hierarchical and dominated by males. Chimps are more widely distributed and, in terms of population size, far more successful, because bonobos are restricted to one small African range. Are these facts related, and related to genes and lifestyle? That will be interesting to find out too. Possibly also depressing.
Pan range. The red blob is where bonobos live. The other colors show ranges of chimp species.