As Britain prepares to debate a provision in Parliament to allow the creation of chimeric hybrids of humans and animals (see blog of May 24, 2007), the Catholic bishops of England and Wales have told a joint committee in the British legislature that these chimeras should be allowed to go to term and be born.

What these Catholic prelates object to is the proposed destruction of chimeric embryos after 14 days. They believe that embryos that are partially human should be implanted in human mothers, and that they should be afforded all the rights of a 100 percent human. According to a recent article in London's Telegraph,

The bishops, who believe that life begins at conception, said that they opposed the creation of any embryo solely for research, but they were also anxious to limit the destruction of such life once it had been brought into existence.

In their submission to the committee, they said: "At the very least, embryos with a preponderance of human genes should be assumed to be embryonic human beings, and should be treated accordingly.

"In particular, it should not be a crime to transfer them, or other human embryos, to the body of the woman providing the ovum, in cases where a human ovum has been used to create them.

"Such a woman is the genetic mother, or partial mother, of the embryo; should she have a change of heart and wish to carry her child to term, she should not be prevented from doing so."

In the fifteenth and sixteenth centuries, astronomers sanctioned by the Catholic Church, such as Christopher Clavius, labored to create a scientific cosmological framework that conformed to both church dogma and the latest observations and data coming from astronomers, such as Nicolas Copernicus, that contradicted the dogma that the earth was at the center of the universe. Attempts to reconcile the two positions led to convoluted and bizarre justifications that were eventually abandoned by nearly everyone.

Arguing that hybrid species with human components deserve to be born requires similar leaps of logic. For instance, if one truly believes that a partially human embryo is a full human, then what about all the animals that share a preponderance of DNA with us humans already, such as other primates, dogs, and mice? What percentage of "human" DNA, which is not exclusively human anyway, makes an organism truly "human"?

Figuring out what is human and what is not is an intriguing question as scientists begin to create human-hybrid embryos, but that's a separate issue from what the bishops are discussing. What they really oppose is human embryos being used for research or treatment, and then destroyed. For now, almost no one wants these bundles of inter-species DNA to go to term. That's not the point. The idea is to develop therapies using hybrid embryos to treat and cure disease. Creating a dog-person is not on anyone's agenda.

As microbiologists scour the earth's most inaccessible places to find ever more weird--and potentially useful--microbugs, I'm half-expecting a new reality show to pop up on the Sci-Fi Channel, or perhaps ESPN-5: Extreme Microbes!

Scientists studying the tiniest of bugs have long traveled to peculiar locales, but now the entire field has been invigorated afresh by the new age of metagenomics--the study of groupings of bacteria found in, say, a bucket of water, a patch of human skin, or a spade full of muck. Armed with sophisticated new technologies to identify millions of different kinds of bacteria inhabiting a specific mini environment, the new "metageneticists" are deploying to nooks and crannies ranging from acid spills to deep caverns in search of microbial communities.

In News@Nature.com, writer Josie Glausiusz describes a spelunking expedition led by microbiologist Diana Northup a thousand feet below the earth, deep into New Mexico's Lechuguilla Cave. She and her team from the University of New Mexico hiked through tangled miles of passageways while rappelling down pits, traversing perilous edges of cliffs, and tramping around underground lakes on their way to collect bacteria that deposit manganese crusts and oxidized iron on cavern walls. Northup is also part of a multiple-university consortium appropriately dubbed SLIME--Subsurface Life in Mineral Environments.

A previous attempt by Northup to snatch up a batch of manganese- and iron-dropping critters failed to produce results because she and her team inadvertently contaminated their samples with fungi that they had brought in on their hiking boots. Back in the lab, the fungi had popped up like weeds in the agar plates when Northup tried to grow the bacteria. This time the team brought clean suits--a misnomer for a posse of microbe hunters who were exceptionally filthy with sweat and muck after their subterranean trek.

Northup also decided to take no chances in growing her samples, so she brought in glass tubes to get her bugs started in their own environment of absolute darkness, cool temperatures, and high humidity. Scientists have found that the classic method for growing bacteria--adding samples to agar-rich petri dishes--doesn't work for an estimated 99.9 percent of microbes, which thrive best in their own ecological soup. This is one reason that metagenomics is taking off. Another is that advances in technology now allow researchers to sequence all DNA in a meta sample to find out how many species and gene variants appear in a given eco niche.

Perhaps the best known metagenomicist is J. Craig Venter, whose Sorcerer II Global Ocean Sampling Expedition announced in March that it had discovered six million new genes and thousands of new protein families, some of which may offer novel solutions for storing and producing energy, among other possibilities. Others are finding microbes that might clean up pollution or produce newfangled antibiotics.

Writer Glausiusz describes the search for antibiotics in her article, as well as a nascent move to commercialize discoveries resulting from the search for slime:

Meanwhile, Kim Lewis and Slava Epstein of Northeastern University in Boston, Massachusetts, are trolling the depths of the uncultured for new antibiotics using a diffusion chamber in which microbes are suffused in the conditions of their natural environment--soil, for example, or sea water plus marine sediments. Lewis and Epstein have founded the company NovoBiotic to capitalize on their cultures. "The practical benefits are enormous," Lewis says. "If you want to discover new stuff, you want to go to organisms you haven't seen before. It's reasonable to assume that 99% of the remaining bacteria will have at least some useful antibiotics."

The spelunking Northup has begun to find antibiotics in her samples. Initially, though, she strove to grow crust-forming cave bacteria to understand their basic biology. "One of the reasons we culture rather than do DNA sequences is because we want to catch them in the act of precipitating the minerals, so that we can say definitely, 'These guys can do it,'" she says.

I encourage you to read the entire article on News@Nature.com; it's creepy-crawly stuff and utterly fascinating. I also suggest that you attend Technology Review's Emerging Technologies Conference at MIT from September 25 through 27, where I will be moderating a panel on metagenomics.

Glausiusz, Josie, "Extreme culture: From acid mine drainage to the bowels of the Earth," Josie Glausiusz reports how researchers are taking great pains to grow recalcitrant bacteria, Nature, Published online: 20 June 2007; | doi:10.1038/447905a

Around 1.9 million years ago, something extraordinary happened to the chimp-like hominids called Homo erectus. Their brains began to enlarge, becoming double the size of those of chimpanzees. Several theories are beginning to coalesce about why this happened. One is that early people began to eat more and better meat around this time, which allowed more calories to be consumed faster. This led to a shrinking of gastrointestinal organs and an increase in brain size that essentially traded guts for gray matter.

Our big brains need this extra energy. Modern humans eat about the same number of calories as other primates that approximate their weight, but we suck up an average of 25 percent of our body's energy expenditure, compared with the 8 percent sucked up by apes. Human babies use 60 percent of their energy to feed their heads.

Anthropologists have assumed that H. erectus ate their burgers and steaks raw, since most early fire pits discovered so far date back about 500,000 years, with the oldest, in Israel, dating back 790,000 years. Charred stones and tools associated with human sites have been discovered that date back as much as 1.5 million years, but these might have been naturally occurring fires.

Now Harvard University's Richard Wrangham has provided some evidence that the very distant ancestors of America's top chefs indeed may have learned to cook their antelope and rabbit. Cooking makes both plants and meat softer and easier to chew, providing more calories with less effort. What's more, human teeth got smaller and duller at around this time, which is the opposite of what would have happened if people had had to rip and chew lots of raw meat.

Wrangham worked with Stephen Secor, an animal physiologist from the University of Alabama at Tuscaloosa, who ran experiments to test the energy required by pythons to consume cooked versus raw meat; Secor also ran experiments on mice to gauge the impact of cooked versus raw meat. The snakes used almost 25 percent less energy chowing down cooked meat; the mice gained more weight and grew slightly longer. The fast turnaround in the mice indicates that cooked meat might have had a quick and dramatic evolutionary impact on early people.

Reducing the time and energy required to chew and digest raw meat means more energy available for other uses--such as feeding a voracious brain that's getting bigger and bigger. Wrangham also thinks that the modern rise in the consumption of cooked meat may contribute to the obesity epidemic; the same goes for processed food, which is even easier to eat and digest. Wrangham presented his findings at a recent paleoanthropology meeting in Cambridge, in the United Kingdom.

Paleoanthropologists are excited by Wrangham's findings and provocative ideas, but the absence of definitive proof of campfires appearing at the same time that human brains doubled in size is a problem. Many still believe that humanity's first cooked meal came much later--about 800,000 to 500,000 years ago, when the human noggin began growing again, expanding by about 30 percent into the modern-size brain.

One question that I'd like to ask evolutionary biologists and paleoanthropologists is why the huge expansion of our brains led to such seemingly unique traits in humans like advanced language skills and acute self-awareness. Would these same traits develop in other mammals if they were fed a diet of broiled beef over several generations? I wonder how many generations of mice it would take to replicate what happened to us--that is, I'd like to see if mouse brains double or triple in size, and also what our furry little friends would do with all that extra neural material.

Citation:

Science 15 June 2007:Vol. 316. no. 5831, pp. 1558 - 1560 DOI: 10.1126/science.316.5831.1558