In astronomy, some words start out as proper nouns: Sun, Moon, Earth, Jupiter. We realized that other stars are also glowing balls of gas like our Sun, and so we talk about the night sky as being full of suns. We also learned that other planets have moons like ours, and so we have our Moon and dozens of moons elsewhere in the solar system. I think that soon we will see lowercase earths and jupiters, as we can talk with more and more confidence about planets around other stars, and compare them to the planets around our local star.

The question of whether or not there is intelligent life on other planets is an important one for us as thinking meat. We want to know if there are other thinking beings out there, or if we are alone in the cosmos. Written records of humankind’s thoughts on the question go back to the early Greek philosophers, although we have taken different attitudes toward it over the centuries. We are finally in a position to at least discover whether or not life exists elsewhere in the universe, if not to locate intelligent life for sure.

Early questioners had no way to discover what was going on even on the surface of the moon, a mere quarter of a million miles away, much less what kind of planets might be in orbit around distant stars. It took us several centuries of telescopic observing before we had identified all the planets of our own solar system, and then suddenly at the end of the twentieth century we entered an amazing period of discovery as astronomers sought and found evidence of planets orbiting other stars. So far they have identified 154 planets around normal stars, including 14 planetary systems of more than one planet, plus some possible planets orbiting pulsars. (For the latest numbers, see the Catalogue of Extrasolar Planets.) What we’ve been able to detect so far from Earth is mostly large planets; the smallest one so far around a normal star is 14 times the size of Earth, but it’s in a very unearthlike orbit (very close to its parent star). Astronomers believe it’s likely that they have even gotten an image of an extrasolar planet, more massive than Jupiter and orbiting a brown dwarf, and another image of a planet orbiting a very young star. (However, the latter might turn out to be too massive to be a planet.) [April 30, 2005: The European Southern Observatory has issued a press release confirming that the former is indeed an extrasolar planet orbiting the brown dwarf.]

NASA has three missions in the works that will follow up on and complement the ongoing ground-based discoveries. These missions will use a variety of techniques to search for extrasolar planets, in particular those that are similar to Earth and are in the habitable zone for their parent star (i.e., at a distance where liquid water is possible). Furthermore, these missions should increase the amount of data we have about planetary systems: for each system, how many planets there are and their sizes and orbits.

With these missions and ongoing ground-based discoveries, we’ll have the basis for a broad comparative study of planetary systems. The planetary systems discovered so far from the ground do not resemble our own very closely; the big planets in these systems are generally much closer in to their stars than the big planets in ours. As we have more data to work with, we can begin to figure out how planetary systems form and how many of the various types there are in the nearby universe. As thinking-meat achievements go, this one is shaping up to be spectacular.

The Kepler mission will look for the ever-so-slight but regular dimming of a star when its planets pass in front of it, or transit. Kepler is scheduled to launch in October of 2007, and will watch 100,000 stars for four years, looking for tiny repeated dips in starlight that should occur if a planet is periodically blocking part of its star’s light as it transits the star.

It takes a very sensitive photometer to measure this decrease in starlight; Kepler’s photometer will be able to measure a change in brightness of about 100 parts per million. Once such a dimming is observed, we can calculate the planet’s orbit from the length of time that the star’s light is decreased. By measuring how much the star’s light is decreased, we can calculate the size of the planet.

Keep in mind that the further out a planet is, the more slowly it circles its star. If you were viewing the solar system from far away and edge on, you’d see the Earth cross the face of the Sun every year; Mars, which is the next-furthest planet from the Sun, would transit every two years. By observing the same stars continuously for four years, Kepler would be able to see four transits for an Earth-like planet orbiting in the habitable zone of a Sun-like star, and fewer transits for planets further out. Kepler can find planets as small as Mercury, but is optimized to search for Earth-sized planets. Kepler should give us a better idea of how many stars have terrestrial planets.

If Kepler finds any terrestrial planets, we can look more closely at them with later missions. Kepler should also give us a much broader data set for comparing the planetary systems.

SIM PlanetQuest, which is slated for launch in 2011, will look for the telltale wobble, very tiny but detectable, of a star being tugged on by its planets. Since the star is very large compared to the planet, the gravitational influence that the star has on the planet is much much greater than the influence that the planet has on the star. However, if you look carefully enough, you can see that a star wobbles very slightly but regularly as the planet orbits it.

(Many of the ground-based discoveries, by the way, are based on detecting this same small wobble. From the ground, however, what researchers look for is very small periodic Doppler shifts in a star’s spectrum, redward and blueward as the star moves away from and toward us.)

SIM stands for Space Interferometry Mission, the original name for this mission. Interferometry is the process of combining light from two or more telescopes to simulate a single telescope of much bigger light-gathering capacity. The Very Large Array (VLA) of radio telescopes in New Mexico uses interferometry, which is easier to do with longer waves like radio waves. To do it with the much shorter wavelengths of visible light, it’s best to go into space. SIM PlanetQuest will use visible-light interferometry to measure the positions of stars much more accurately than we have been able to so far, and the accuracy of this positioning will also enable us to search for the signs of planets around these stars.

SIM PlanetQuest will look at the closest 250 stars in search of terrestrial planets. This is the hardest part of SIM, and will require the most precise measurements (one-millionth of an arcsecond, which is the thickness of a nickel on the moon as seen from the Earth). SIM will also survey a larger group of about 2,000 stars with a lower accuracy, looking for Neptune-sized and bigger planets to try to figure out how many of them there might be in this neck of the galactic woods. A third goal for the mission is to look for Jupiter-mass planets around young stars. The fact that so many of the planetary systems we’ve discovered from Earth are so different from our own has sparked a great deal of curiosity about how these systems and their planets are formed. By looking at young systems, the SIM mission might be able to shed some light on the early development of planetary systems.

The Terrestrial Planet Finder (TPF) is the most ambitious of all the missions. It has two complementary parts: an interferometer that works in the infrared (not visible light like SIM), and a coronagraph. The idea behind the coronagraph is to observe planets directly by blocking the light of the parent star so that the comparatively dim planets have a chance to appear. Since the star is very bright and the planet very dim in comparison, this is a daunting task, and the smaller the planet, the harder it will be. (Note that the extrasolar planets possibly imaged so far from Earth were more massive than Jupiter.)

TPF, scheduled to launch between 2014 and 2020, will study up to 150 stars within 45 light years of Earth. In addition to detecting terrestrial planets, TPF would also analyze the spectra of any planets it finds. By breaking a planet’s light down into its component colors, TPF will reveal the chemical composition of the planet. This is where it gets extremely exciting, because in addition to detecting a planetary atmosphere and telling us what it’s made of, TPF can also look for biomarkers like the presence of molecular oxygen and methane, and also for chlorophyll.

If you could make such a spectrum for Earth, you would compress all of this planet’s biodiversity, all of the living processes, into a single diagram, dense with information but obviously not a complete picture of the planet. What would it be like to see a similar diagram for a totally alien world? If we have the luck to look in the right place, I wouldn’t really be surprised to see such a life-revealing spectrum. Earth harbors life in such unlikely and downright hostile places that I suppose that other planets might well harbor at least simple forms of life, although I’d guess that highly complex, intelligent beings are not very common. But who knows what we will find?

Two European missions, Corot and Darwin, will also look for extrasolar planets and signs of life.

Why should we look? I’m not sure it provides economic justification that would satisfy a financial analyst, but my answer is that I can’t imagine us not looking. It’s part of what we do best. Humans are curious about their environment. Maybe this is an adaptation; curious hominids might well do better at surviving and reproducing than slack-jawed dullards who lack the energy or inclination to see what’s over the next hill or whether there’s an easier way to do something. Deep space is not our immediate environment, true, and it doesn’t have much to contribute to our capacities for survival or reproduction (I don’t believe that space colonization offers much hope for relieving our resource problems on Earth, for example). But I don’t think we can turn our curiosity off; even if it evolved as an aid in certain specific situations, it’s a part of us now that we tend to apply in all kinds of other situations.

And the question of whether we’re unique or not in the universe is a very fundamental question, although on a huge scale, about our place in the natural environment. The discovery of even simple life on another planet would be bound to cause deep changes in our worldview. (In addition to the jubilation and excitement, and the possibility of a new science of comparative biology, I can imagine the conspiracy theories already, saying that the observations are faked. I just wish I had the imagination to weave a good story about why people would say they are faked, so I could write a blockbuster novel and make big bucks.)

Geoffrey Marcy, who with his team discovered over half of the extrasolar planets we know so far, recently gave a series of talks at Indiana University that provided an excellent look at the state of extrasolar planetary science. (If you ever get a chance to hear him talk, by all means go!) In particular, he gave a compelling presentation on why we should look for other life in the universe.

One of his points was that we have some inherited traits that are counterproductive for us now (e.g., xenophobia and territoriality), but we also have some favorable attributes like curiosity and the capacity for compassion, and it’s an open question which aspects will prevail. I think that our hope as a species lies in nurturing the favorable traits, in particular curiosity. If exploration is one of the things we humans do, then let us do it well.

Looking for other life in the cosmos implies a belief in our own future—why bother looking if we believe that we ourselves are to be extinguished soon because of our own environmental and political mistakes? Furthermore, if we value life enough to seek it out among the stars, to me that goes hand in hand with valuing it enough to try to preserve it, in all its diversity, down here on this planet. There are other ways we can express both our curiosity and our belief in the future, but this is one of the important ones. May the meat keep on thinking, long into the future.

The Edge recently published a thought-provoking essay by Armand Leroi, plus several responses from others, on the subject of the genetic factors underlying normal human differences, particularly those between races. The topic of biological differences between groups of people is subject to all kinds of misuse and abuse for social or political reasons, so some are reluctant to study it, but on the other hand, maybe more knowledge is a better way to combat that misuse than keeping silent. This essay provides some interesting food for thought, at any rate.

http://www.edge.org/3rd_culture/leroi05/leroi05_index.html

I’m not sure I remember exactly when I first started to use the phrase “thinking meat”. It might have been when I was reading an article about whether or not exposure to video display terminals causes miscarriages. I was struck by the way people want to know why something happens, so that they can take action to avoid having it happen to them, or perhaps even comfort themselves by thinking “That couldn’t happen to me because… .” A surprisingly high fraction of pregnancies just don’t work; the embryo just isn’t viable. But a lot of people don’t want to accept that we’re subject to the vagaries of biological chance. Because we’re conscious and become emotionally attached to each other, we suffer more from things that leave plenty of other creatures untroubled. In nature, lots of creatures have far more eggs or offspring than can survive, and the mother turtle, for example, doesn’t grieve because a lot of the young die. But it’s different for us.

So the thinking meat dilemma began with a curiosity about how people live with being meat, subject to all of the infections and injuries and wear and tear and deterioration that meat can suffer, while being conscious loving beings with feelings and vivid imaginations, who want to be here and fear having to leave, who grow attached to others just as vulnerable.

It can be scary to be a mortal animal walking around an uncertain world. You probably saw some of the horrifying images from the aftermath of the tsunami in the Indian Ocean on December 26, 2004, not to mention the images of people leaping from the World Trade Center to their deaths on September 11. And as awful as those things were, what can happen to the brain is worse. Think of Alzheimer’s disease, for example. Recently, the finance manager of the city of Phoenix came to a horrifying end, climbing onto the top of his car while he was driving down the street and then falling or jumping to his death. By nature a quiet and reserved man, he behaved this way because of parasites in his brain, the result of an improperly cooked meal he ate in Mexico. If you see the brain as the source of our consciousness, our memories, our feelings, and our personalities, and you realize the brain is so fragile, our vulnerability can sometimes be a bitter pill to swallow. And if our own vulnerability is hard to take, the vulnerability of those we love is even more poignant.

Religion is one obvious way that people have dealt with their vulnerability and their subjection to natural laws that seem capricious. The dualism at the heart of much of Western religion sidesteps the thinking meat problem by claiming that we are something besides just meat, that we possess immortal souls that live beyond whatever happens to the body that we inhabit temporarily. I see no reason to believe in this dualistic view, but whether you believe it or not, religious belief obviously plays a large and complicated role in people’s attempts to resolve the thinking meat problem.

I believe that our brains and our minds are one and the same. In part, the Thinking Meat Project is about the journey from thinking in terms of a mind-body split to thinking in terms of embodied cognition, embodied consciousness, embodied feeling. I began this journey years ago when I left the church, and am still figuring out how to find meaning and purpose in a world where we are animals that think and where our deepest passions and values, which feel so personal and chosen, are partly a result of our biological makeup. As science learns more and more about our physical being, thoughtful people everywhere are having to make the same journey.

One of the hardest things to give up when I left the church was the idea of life after death. If our minds arise from the activity of our brains, then when we die, we’re gone. But another part of the thinking meat problem has to do with how we’re in some ways not entirely gone. When my mother died four and a half years ago, my sister’s mother-in-law said to me, “She’s not really gone, you know.” Well, I can’t call her on the phone, or send her a birthday present, or tell her about her grandson going off to grad school. But in another sense, she is still here. My siblings and I are carrying some of my mother’s genes. We and all the others who were close to her have been shaped in countless ways by her presence in our lives, and you can still see the imprint she left even though she herself is gone. She left behind memories and turns of phrase. Cultures around the world have beliefs about the continuing presence of the dead in the lives of the living. This is one of the things we have to understand, as thinking meat.

It’s not all sadness, being thinking meat. We’ve found ways to cope, besides religion. Several years ago, after 9/11 and after my mother died, I was at a world music festival, listening to the performers explaining the sources of their songs. A Cajun band sang about homesickness for Acadia, and a Mongolian woman sang the stories from her female forebears who missed their men-folk when the men were out on long journeys to bring back salt. It occurred to me then that maybe art is one answer to the thinking meat problem. We want our experiences to mean something, and we also want to know that other people have felt the same way; art tells us that we are not alone. In the process of sharing our experiences, art lets us take unpleasant facts and transform them into something beautiful, or funny, or thought-provoking. Maybe we can learn from other people, at least that they survived painful situations if not how they survived. Sharing meat, my son Greg said when I tried to explain this part to him.

Art also eases the pressure of finitude a bit. Life is too short, but if you can squeeze in other people’s experiences in addition to your own, at least you’re getting the most you can out of your time here. You can reach into the past by experiencing the work of other minds and other imaginations, and some of us are lucky enough to leave behind words or images or music that will reach into the future. The origins and functions of art are part of the Thinking Meat Project. This takes the project into such rich topics as cognition, memory, language, narrative, and metaphor.

And there is endless entertainment and intellectual exercise in being thinking meat. Our minds can get up to things that we don’t really understand (yet). Various quirks—collective and individual—of memory, language, and cognition can provide all kinds of fodder for studying how we think. My brain seems like a black box sometimes; I turn a crank and something comes out, but sometimes I have to wonder “Where did that come from?”

There is amusement to be had in the ups and downs of the meat too, if you look hard enough. (“If we couldn’t laugh, we would all go insane,” sang Jimmy Buffett, and sometimes you just have to laugh.) Anyone who has survived puberty, pregnancy, illness, injury, or aging is aware of how mysterious the ways of the body can be. Maybe my body seems fundamentally mysterious to me (in a way that my mind is not) because I’m very verbal, so I pay more attention to the part of me that creates the stream of words that constitutes my conscious life, and far less attention to bodily cues about what’s going on. But I think to some degree everyone has felt like multiple beings. Konrad Lorenz describes a life as a “great parliament of instincts”, and while I’m not sure which instincts he was talking about, the phrase resonates for me because sometimes I can hear the individual voices in the parliament. The mouth savors a flavor and wants to go on eating, but the stomach says, “Enough.” Or mouth and gut agree (“More!”) but the mind, having recently digested some dietary advice, says, “This is not doing my cholesterol levels any good.”

And that leads to questions of identity. Which of our many manifestations represent who we really are? Women who suffer from PMS refer jokingly to “the evil twin” who takes over sometimes, and some of the self-help books of the 1980s advised you to mind your Inner Child. And we certainly show different parts of ourselves to different people; my parents see a different me than my children do, and my co-workers see someone else again. They’re all linked by many shared characteristics, but they’re certainly not the same persona. So which one is me? Or am I an amalgam of all of them? Maybe there’s a higher “me” that chooses which one to be at each moment.

The question goes beyond different behaviors, down to the biochemical level. It’s increasingly common these days to invoke neurochemistry or various substances to explain some of our behavior: a grump is serotonin-deprived; some people should not be talked to in the morning until after their second cup of coffee. Or maybe we joke about someone inheriting a tightwad gene. The Thinking Meat Project is about how our biochemistry, inherited and induced, combines with our environments and histories to create our behavior and our personalities.

Assuming that a mix of biology and environment has shaped us, what is “natural”? Where do we find our balance between respecting and cherishing nature (our physical natures, our emotional natures, Nature out there, all those sunsets and mountains and such), and working to improve it? I wear glasses and I take blood pressure medication, but I would hesitate considerably before taking an antidepressant if one were ever prescribed for me. If I could have identified the heritable glitch that causes my hypertension, would I have wanted to make sure my sons didn’t inherit it from me? Sure, I think, except that how would I know we understand everything about the complex factors that go into regulating blood pressure, and that eliminating this problem wouldn’t cause something even worse? And the questions get even tougher as we think about things like personality traits or emotional conditions.

In the wider world, I want some wild places left undisturbed, and I love to see natural beauty in its wild state, but I also enjoy the beauty that people can create in the areas where they live, in gardens and buildings that fit into natural settings but also in some sense improve upon them. I say that I value life as precious, but I don’t hesitate to end the life of a mouse in my kitchen. Everyone needs to decide on a place on the spectrum between total acceptance of nature and total rejection of it. This is part of our dilemma as thinking meat, as beings that are a part of nature and yet somehow apart from it.

Animals are commonly perceived as being closer to nature than we are, and we think of that in two ways. On the one hand, we envy the animals their innocence and simplicity, and we admire the fact that they don’t lie awake at night fretting over their place in the universe. We long to be as free as the animals to express our physical yearnings and pursue our comforts. In the words of the poet Mary Oliver, we want to let the soft animals of our bodies love what they love. Animals don’t build guns or bombs.

This view is, of course, exaggerated. Some animals commit infanticide, for example. They’re not as innocent as we imagine.

So we don’t want to be “just animals”, on the level of the beasts. We want to rise above our animal selves and be something more: civilized, altruistic. Animals eat other animals, but some humans argue that we should be better than that. Predators often pick out the weak or the sick and the young to prey on, and I can see that a breed of creatures becomes smarter and stronger and quicker under that kind of pressure. Yet I am moved by the haunting story that Loren Eiseley tells of a prehistoric human who lost an arm somehow, a dreadful and by all rights deadly loss in that time and place. The skeletal remains of this person showed that he had survived the injury and lived on afterwards, presumably tended lovingly by someone who valued his survival beyond his use as a food provider. I am touched at that defiance of the physical laws that bind us.

The view of ourselves as morally elevated is also exaggerated. Some animals are capable of altruism, for example; we’re not as far removed from them as we’d like to think. The truth is somewhere in the middle.

We do have an amazing ability to discover things about the universe we live in and about ourselves. Although our minds didn’t evolve in a world that required them to calculate the distance to a star or deduce facts about the genome from long complicated chains of evidence, we can do these things. There’s no particular reason we should be able to understand every last thing about how things work, and I’m curious about where the limits are. But mostly I’m enjoying what we’re finding in the meanwhile: the knowledge of the earth’s history and our own, lost in deep time but uncovered to some degree by patient curious humans; the images of the universe returned by the Hubble Space Telescope; the details of the human genome that we are only beginning to understand. Just in the past ten years or so, we have discovered planets around other stars. This gives us fuel for speculation on the age-old question of whether or not we are alone here in the universe. I am inclined to believe in the hypothesis put forth by Ward and Brownlee in Rare Earth, that life may be common but conscious life much less so. When I think of the many factors that had to come together to make our presence here possible, I am one happy hominid to be walking around on this planet.

The concept of thinking meat thus grew out of news stories, family situations, and lots of reading. When I started compiling a reading list last year to organize my efforts, I started to think in terms of the Thinking Meat Project. As broad as the project is, there is a core idea, or maybe a Gestalt, that links the many ideas together. After thinking in terms of Thinking Meat for awhile, you can recognize that Gestalt as you’re browsing the bookstore or reading the paper or cruising the Web. This site is an attempt to provide resources for others who are interested in thinking meat, to present some of the writing I’ve done on the topic, and also, I hope, to gather an online community of curious meat.

Thanks for stopping by. I hope you’ll come back often.