Last fall, I described a book I was highly anticipating called The Immortal Life of Henrietta Lacks by Rebecca Skloot. And unless you’ve been hiding under a rock somewhere, you’ve no doubt already read excerpts and phenomenal reviews, seen it covered on television, heard Rebecca on air, and watched it climb the New York Times bestseller list during these first weeks since publication. All of the praise is more than deserved, and I would add that the story of Henrietta Lacks, her family, the immortal HeLa cell line, and the many dimensions to the story that Rebecca does such an extraordinary job of reporting, may just be one of the greatest true stories ever told.

Henrietta’s life wasn’t easy. She lost her parents by the age of four and worked hard alongside her cousins on a tobacco farm while facing the challenge of growing up as an African American woman in the south. After marrying young and having five children, Henrietta died at age 31 from cervical cancer. But around the time of her diagnosis, cancer cells from her cervix—famously known around the world as HeLa cells—were taken from her tumor to be used in research without her knowledge or consent.

HeLa cells were the first living human cells to be successfully grown in culture. They were distributed to scientists around the world and led to the vaccine for polio and many other diseases. HeLa taught scientists about chromosomes and genetic diseases like Down syndrome. They were launched into space to observe how space travel would affect human cells. They were inundated with toxins to understand cell response to different substances. They led to advances such as in vitro fertilization and helped win many Nobel Prizes. Over time, HeLa cells were cultured and copied and shipped and sold so many times, it’s estimated combined they would weigh over 50 million metric tons (equal to at least 100 Empire State Buildings).

Henrietta’s family was not told any of this for years. Her children and husband did not hear how their mother’s cells revolutionized medicine over and over as they were tested by researchers for seemingly ambiguous reasons. For-profit companies made billions off Henrietta’s cells, while those she cared about most often couldn’t even afford healthcare.

The Immortal Life of Henrietta Lacks is about the life, death, and legacy of one of history’s most important individuals who all but lost her identity. Rebecca elegantly shares her true story which deals with science, ethics, and equality. The book spans nearly a century, and reflects the changing landscape of medicine, and the good, bad, and ugly side of research.

Most of all, it’s a human story that touches all of us. It’s beautiful, poignant, interdisciplinary, and should be required reading for every high school student.

I will have more to say about this wonderful book soon, but for now I leave readers with a single suggestion: Read it.

Welcome to this week’s installment of the From Eternity to Here book club. We next take a look at Chapter Seven, “Running Time Backward.” Now we’re getting serious! (Where “serious” means “fun.”)

Excerpt:

The important concept isn’t “time reversal” at all, but the similar-sounding notion of reversibility–our ability to reconstruct the past from the present, as Laplace’s Demon is purportedly able to do, even if it’s more complicated than simply reversing time. And the key concept that ensures reversibility is conservation of information–if the information needed to specify the state of the world is preserved as time passes, we will always be able to run the clock backward and recover any previous state. That’s where the real puzzle concerning the arrow of time will arise.

With this chapter we begin Part Three of the book, which is the most important (and my favorite) of the four parts. Over the course of the next five chapters we’ll be exploring the statistical definition of entropy and its various implications, as well as the puzzles it raises.

But before getting to entropy, and the arrow of time that depends on it, we first have to understand life without an arrow of time. The only reason the Second Law is puzzling is because the rules of fundamental physics don’t exhibit an arrow of time on their own — they’re perfectly reversible. In this chapter we discuss what “reversible” really means, and contrast it with “time reversal invariance,” which is related by not quite the same. If a theory is both reversible and time-translation invariant (same rules at all times), it’s always possible to define time reversal so that your theory is invariant under it. (E.g. in most quantum field theories, “CPT” does the trick.)

Reversibility is a very deep idea; it implies that the state of the universe at any one moment in time is sufficient (along with the laws of physics) to precisely determine the state at any other time, past or future. But not many popular physics books spend much time explaining this idea. So we reach all the way back to very simplified models of discrete systems on a lattice (”checkerboard world”). What we’re after is an understanding of what it really means to have “laws of physics” in the first place — rules that the universe obeys as it evolves through time. That lets us explore different kinds of rules, in particular ones that are and are not reversible.

Along the way we talk about time-reversal invariance in the weak interactions of particle physics, and emphasize how this is not related to the thermodynamic arrow of time that is our concern in this book. Which gives me a good excuse to quote a touching passage from C.S. Wu. This chapter has everything, I tell you.

Sure, creatures that reproduce asexually get to avoid some of the hangups that come with sex, but the strategy brings its own problems. First and foremost, how do you prevent genetic deterioration without the fresh infusion of new genes that results from the mixing of male and female DNA? For the all-female whiptail lizard, the solution is to hedge its bets.

In a study forthcoming in Nature, researcher Peter Baumann found that each whiptail lizard egg cells contains twice the number of chromosomes you’d expect. In the fertilized egg cell of a sexually reproducing lizard species, you’d expect to see much what you see in humans—23 chromosomes from the father and 23 from the mother combining into 46. (Most human cells contain 46 chromosomes, but egg and sperm cells contain only 23, so that they can combine to give an offspring a compete, but genetically new, set of chromosomes.)

But the whiptail eggs instead begin with two identical copies of each of their mother’s chromosomes, for a total of 92. Those chromosomes then pair with their identical duplicates, and after two cell divisions, a mature egg with 46 chromosomes is produced. Since crossing-over during the cell divisions occurs only between pairs of identical chromosomes, the lizard that develops from the unfertilized egg is identical to its mother [The New York Times].

Curiously, the whiptail lizards came to be through the fusion of two other lizard species, Baumann says. That gave it a rich genetic diversity, but without sex the lizards needed a new way to maintain that diversity. “There’s an absence of sperm, and genetic information is never provided by another source. Anything that’s lost is lost for good” [Wired.com], Baumann says. This trick he found provides a tidy explanation for how these all-female lizards maintain those rich genetics.

Still, while the whiptail’s trick allows for generation after generation of identical lizards, that’s not necessarily advantageous for long term survival. Unless an animal can recombine the DNA they already have, they will produce an offspring with an identical set of chromosomes, in which any genetic weakness, such as disease susceptibility or physical mutation, would have no chance to be overridden by outside genetic material from a mate [Scientific American]. Asexual reproduction is beneficial in the short run, and species like Komodo dragons will do it if they have to. But relying on it exclusively might cost the whiptails in the long run, especially if they should need to adapt to a changing habitat.

There are other creative solutions invented by other asexual species, like the bdelloid rotifers. Unfortunately, though, lizards probably can’t steal the rotifers’ trick of ripping apart their genome and stealing foreign DNA from the surrounding environment.

Related Content:
80beats: Sexless Sea Creatures Steal Foreign Genes
DISCOVER: The Real Dirty Secret About Sex (Life doesn’t need it, so why do we do it?)
DISCOVER: A Good Reason For Sex
DISCOVER: 20 Things You Didn’t Know About… Sex

Image: Peter Baumann

Sometimes I’m surprised by something I thought I knew, and found out I didn’t, not really.

For your consideration: NGC 1427A, a dwarf galaxy.

[Click to unendwarfenate.]

I’ve seen pictures of this little guy before. It’s a small galaxy, maybe 20,000 light years across (the Milky Way is 5 times that size), and part of the Fornax cluster, a small but rich cluster of galaxies about 60 million light years away. The picture here was taken with the monster 8.2 meter Very Large Telescope in Chile, and uses filters that give a somewhat true-color appearance, though it also accentuates warm hydrogen (the pinkish glow).

Even though I’ve looked at it before, I don’t think I really saw it, because the boomerang shape is obvious, and to anyone familiar with galaxy dynamics the reason behind it is obvious too. Maybe it’ll help to know that this diminutive galaxy is screaming through the Fornax cluster at 600 kilometers per second, a ridiculously high speed.

See it now? NGC 1427A looks like it’s got a swept-back shape because it’s being swept back. In between galaxies there is an ethereally-thin fog of gas, but there’s enough there to have an effect on a passing galaxy. The boomerang shape of the galaxy is because that side is facing into the wind, so to speak, and being compressed. The pink curve in the image is due to rigorous star-formation going on there, where the gas clouds are collapsing from the pressure and birthing stars at a prodigious rate.

Looking at this image, it’s so obvious what’s going on I’m surprised I didn’t notice it before. I guess sometimes you miss stuff right under your nose if you’re not paying attention. If you consider 60 mega-light-years under your nose.

Tip o’ the Strömgren sphere to the ESO. Image credit: ESO. 10 extra BA points for anyone who knows what the title’s from. Don’t Google it! That’s cheating.