Arsenic-Based Life

This week, NASA geobiologist Felisa Wolfe-Simon announced the discovery of arsenic-based microbes in Mono Lake in Yosemite National Park. This is a major scientific bombshell that is causing biologists to re-examine much of the conventional wisdom about what life is. All life, from the smallest bacteria to the largest redwood tree, was thought to be based on five elements: Carbon, hydrogen, oxygen, nitrogen, and phosphorus. These elements are crucial ingredients in life’s software – DNA and RNA molecules – as well as life’s fuel – ATP molecules. But now scientists have discovered organisms that use arsenic instead of phosphorus in their biochemistry, which was thought to be impossible. Most organisms are poisoned by arsenic because it is highly reactive, destroying the DNA and ATP found in living cells. But this new species of extremophile not only thrives in a lake with an arsenic concentration 700 times what the EPA deems safe, but actually manages to incorporate it into its DNA and ATP. This is more than just a strange new species with an interesting quirk; many of those are discovered every year. This is a radical redefinition of what “life” is.

Although these microbes appear to have evolved from more traditional forms of life, their mere existence opens up the possibility of a "shadow biosphere" on earth. All known living things have descended from a common ancestor, but what if organisms with other biochemistries are living right under our noses undetected? Might they provide evidence of a second genesis on earth? If life has developed twice, with two different biochemistries, it would prove that the evolution of life on earth was not just a one-in-a-trillion fluke, and would greatly increase the likelihood of life developing on any suitable world.

The discovery of arsenic-based life has important applications in the search for extraterrestrial life, which is where NASA comes in. For ages, scientists have pondered about the possibility of completely new types of life. A handful of astrobiologists (and a slew of science fiction writers) have speculated that extraterrestrial life might be too alien for us to even recognize as life. In fact, this is one possible explanation for Fermi's Paradox, which questions why we haven't already found life if it is commonplace in the universe. In light of this week's discovery, this explanation has become a lot more plausible. Perhaps DNA, reliance on water, and cells are just unique traits of life on earth, and we are barking up the wrong tree if we focus solely on finding them elsewhere.

Others have believed that “life as we know it” was the only type of life possible. This has been the dominant mindset of NASA for several decades, and is the basis of NASA’s search for life. NASA has concentrated its efforts on locating worlds similar to our own, where the conditions exist to permit the development of life as we know it. This generally means finding worlds with water on them, located in the “Goldilocks Zone” of their solar systems where they are neither too hot nor too cold to sustain life. This, of course, has been premised on the assumption that any extraterrestrial life is probably not too different from the life we know.

The discovery of arsenic-based life has cast doubt on this approach. If a new form of life can be found in Yosemite National Park, we can scarcely imagine how different extraterrestrial life must be. NASA’s obsessive search for earth-like planets may be overlooking a huge number of worlds where life may exist, in forms unknown to us earthlings. If it is possible for life to exist with a completely different biochemistry from our own, then it’s equally possible that it could thrive on worlds far different from our own, under conditions that have traditionally been regarded as hostile to life.

NASA will need to do a lot of soul-searching in light of this week’s discovery, and reevaluate how it determines if a world is potentially suitable for life. For the first time in history, a long-standing astrobiological question has been answered: Is “life as we know it” the only type of life possible? We now have our answer: It is not.

The Future of Health Care - The End of Aging

What disease kills 100,000 people every day (usually after a prolonged period of pain and illness), affects nearly everyone, and kills about 90% of people in the industrialized world?

Aubrey de Grey, a renowned gerontologist, is on a quest to eliminate aging. The search for the fountain of youth has confounded humanity for millennia, but de Grey is on more solid scientific ground than most of his predecessors in this field. He has identified what he believes are the seven causes of biological aging – a list which has remained unchanged for the past 30 years – as well as the solutions for dealing with each cause. These solutions are not merely theoretical; they have all been demonstrated in labs, although most of them are many years away from being generally available.

Some casual observers may conclude that it is physically impossible to prevent aging since people have been trying and failing to do so for millennia. But the fact is that there are naturally-occurring examples of cells that do not age. Unfortunately, they’re called cancer cells, and tend to have the nasty side effect of killing people. Nevertheless, they do demonstrate the reality of cells that do not age.

Each cell in our body normally has an hourglass in it; the cell replicates as many times as it can, then commits suicide when the hourglass runs out of sand. But scientists have discovered how to add more sand to the hourglass. It’s an enzyme called telomerase that occurs at the end of DNA strands. Each time our cells divide, the DNA strands become frayed at the end, until eventually they are too unstable and self-destruct. For the discovery of telomerase in 1984 and subsequent analysis of how it relates to aging, three scientists were awarded the 2009 Nobel Prize in Medicine.

There is still a lot of research that needs to be done before it is possible to halt or reverse the aging process in humans. De Grey’s organizations, the SENS Foundation and the Methuselah Foundation, are currently testing life-extension therapies on mice. The Methuselah Foundation offers the MPrize: a reward of up to $4 million to anyone who can extend the lifespan of mice to record-breaking lengths. The goal is to eventually apply this knowledge to increase the human lifespan.

De Grey is not interested in extending the portion of life in which people are old, frail, and sick. His goal is to extend the healthy portion of life, and ultimately to prevent people from ever growing old at all…and reversing the aging process for those who are already elderly. This is not pie-in-the-sky immortality, as it won’t eliminate all causes of death. It would, however, offer the possibility of lifespans of indefinite length. De Grey has explained the concept as the “Longevity Escape Velocity.” Over the past century, medicine has done an excellent job preventing people from dying at young ages, but very little to prevent aging or increase the maximum human lifespan. At the present, medicine is progressing relatively slowly, adding a few weeks to our lifespan every year. When the Genomic Revolution picks up pace within the next few years, it is likely that this will be increased to a few months every year. De Grey hopes that eventually we can attack the root causes of aging itself to add more than one year to the human lifespan every year. He believes that the first person to reach age 1,000 is alive today…and is probably only about ten years younger than the first person to live to age 150.

The concepts of aging and old age are so ingrained in our mindset that we tend to not even think about them. Like anything that is both horrifying and seemingly inevitable, we have a remarkable ability to push aging out of our minds, or even to go through mental contortions to rationalize it as a good thing. Virtually all major life decisions we make – what career to pursue, how much of our money to save, how much risk to take, who to marry, how many children to have, when to retire, what our religious beliefs are, if or when we should go to college – are ultimately premised on the assumption that we will grow old and die, probably between ages 70 and 100. But what if this ceases to be the case? There is almost nothing that would alter our lifestyles, worldviews, beliefs, and culture as profoundly as the end of aging and the mindset that accompanies it.

Modern biology has already discovered theoretical solutions to all of the causes of aging; it is now a matter of applying them and developing solutions that work for human beings.

(The SENS Foundation and the Methuselah Foundation are non-profit organizations under US law. All donations are tax-deductible. If you have some money to donate, these organizations are helping to solve the single worst disease threatening humanity.)

PREDICTIONS:
By 2045 – The aging process has been halted, for all intents and purposes. People no longer grow old beyond their peak healthy age, between 18 and 25.
By 2060 – It is possible to reverse existing damage from the aging process. It is no longer possible to estimate an adult’s chronological age merely by looking at them. Diseases of old age have, for the most part, ceased to be a problem.

The Future of Health Care - The Genomic Revolution

For the first time in decades, we are due for a completely transformational change in health care. We are on the cusp of the Genomic Revolution, and we will start seeing the earliest results in the immediate future. Personal genomics – the practice of tailoring prescriptions, treatments, and lifestyle choices to an individual based on their genes – will soon depose the old paradigm of medicine. No longer will doctors merely give patients the drugs with the highest chance of success; they will be able to predict whether or not the drug will be effective for a specific person. No longer will patients try to base their diet and exercise habits on generic recommendations of what is healthy and what is not; instead, they can determine the healthiest lifestyle for their genetic makeup specifically. Health care will become mostly preventative, rather than reactive.

Why now? What is the driving force behind this paradigm shift? For the first time in human history, we have enough computing power to cheaply and quickly sequence the human genome. In the very near future, nearly everyone will have access to their entire DNA code, which they can carry on their smartphones. When Craig Venter became the first person to have his genome sequenced in 2000 as part of the Human Genome Project, it cost $3 billion and took thirteen years. When James Watson had his genome sequenced in 2007, it cost $2 million and took two months. Today, sequencing a human genome costs about $6,000 and takes a couple weeks. Within the next year, it is very likely that companies will offer genome sequencing for less than $1,000. Some observers view the $1,000 mark as a tipping point: the point at which average people can afford the service, and at which health insurers may start covering it. And after we have $1,000 genomes, $1 genomes won’t be far behind. Let’s not forget that the cost has dropped nearly a thousandfold in the last three years. Fast-forward a few more years, and it is conceivable that the cost of genome sequencing will be essentially nothing. I envision a day in the not-too-distant future when Walgreens and CVS will have self-service genome sequencing machines, as quick, cheap, and user-friendly as self-service photo machines.

Of course, merely knowing one's genetic code is worthless without knowing how to interpret it. While biologists have identified thousands of disease markers, there is vastly more that we don’t know about our genetic code. Some services available now, such as Google-funded 23AndMe, can test DNA to determine one’s predisposition to a narrow range of diseases, but this is only the tip of the iceberg of what is possible. As the cost of genome sequencing approaches zero, nearly everyone will have it done. As the total number of genomes grows from thousands to millions to billions, scientists will have a treasure trove of data to analyze diseases and patient responses to medication. A machine called a microarray allows scientists to compare different DNA sequences and search for correlations. As more and more human genomes are available to be analyzed, patterns will become more evident and it will become much easier to unearth the specific genes associated with certain diseases. Patients who know the diseases for which they are at risk will be able to modify their lifestyle to prevent them from arising.

Those who are unlucky enough to get a disease in spite of (or because of) their lifestyle will have access to much more robust treatments than those currently available. By pinpointing the genetic location of a particular disease, scientists will be able to understand what caused the disease and how it can be reversed. Think of our genetic code like a computer program: Understanding the cause and location of the bugs will enable us to fix them. In the slightly more distant future, it will be possible to directly repair defective genes, such as those that cause cancer, through genetic therapy.

The next ten years will be the most transformative decade in human history for medicine, as we finally unlock the secrets of our genetic code which have been a mystery since the dawn of humanity. The things I have described here are by no means a comprehensive description of the benefits of the Genomic Revolution, and the new paradigm will not be without problems of its own. To be continued in another blog post…

PREDICTIONS:
By 2011 – At least one company offers genome sequencing for $1,000 or less
By 2014 – At least one company offers genome sequencing for $100 or less
By 2019 – Over half of all Americans have had their genomes sequenced
By 2021 – U.S. sales of personalized medicine (i.e. drugs tailored to the patient’s specific genetic profile) are greater than sales of non-personalized, mass-market medicine