What I Learned Today

Did you know that newborns sometimes vomit blood, even when perfectly healthy?

I sure didn’t, nor did my sister. So when this happened, she took her newborn daughter straightaway to the doctor. He explained that this was likely due to my niece having swallowed blood during the birthing process, and in fact nothing to be alarmed about. “How long does this last?” she asked anxiously. “Up to about seven days,” he noted.

I did some more investigation and learned that, indeed, the most likely cause of blood in a newborn’s vomit is “maternal blood”, either swallowed during delivery or from “cracked, raw nipples from breastfeeding”. (Ouch.) While the blood can come from the baby itself, this is actually much less common (although I didn’t find any stats on it); “The Newborn Child” by Johnston et al. agrees. Here’s an interesting case-study-esque version of how a doctor might diagnose such cases. It also describes the diagnostic test (“Apt test”) that is used to determine whether the blood is from the mother or the baby (the latter contains “fetal hemoglobin”). Rather than just citing the name of the test, the same source actually tells you how it works: mix the blood sample with sodium hydroxide, which breaks down adult hemoglobin (turning the sample dark brown) but will have less impact on fetal hemoglobin (which will stay pink). I really appreciate sources (particularly medical ones) that bother to explain the science behind the process, diagnosis, or treatment!

What changes are needed to move from an aquatic existence to one on dry land? According to David Attenborough, a watertight skin, eggs with a hard shell, and stronger skeletal support to combat gravity. The differences between an amphibian’s egg and a tortoise’s egg also go more than shell deep: the embryo has to excrete waste, which in the water is naturally dispersed through the (permeable) egg membrane. On land, embryos instead develop an allantois (from the Greek word for “sausage”), which not only stores waste, but also permits the embryos to breathe. They need oxygen, and again in the water this would occur naturally through the membrane — but with a shell, that’s not possible. The allantois, however, presses against the shell strongly enough to exchange gas, and the embryo is connected to the allantois with blood vessels to treat it somewhat like a lung. Wow.

According to the wikipedia entry, human fetuses also have an allantois, which is inside the umbilical cord!

Darwin was first inspired about natural selection when observing the strikingly different tortoise shell shapes observed in the Galapagos Islands — distinct enough that a tortoise’s home island could be immediately inferred from its shell (well, or its taste):

The inhabitants, as I have said, state that they can distinguish the tortoises from the different islands; and that they differ not only in size, but in other characters. Captain Porter has described those from Charles and from the nearest island to it, namely, Hood Island, as having their shells in front thick and turned up like a Spanish saddle, whilst the tortoises from James Island are rounder, blacker, and have a better taste when cooked. — Charles Darwin, Journal of Researches, 1845, p. 394

Unfortunately, he didn’t record carefully enough which island each of his specimens came from, so on his return to England he instead used the less dramatic finch-beak example to illustrate his theory. He himself knew almost nothing about birds; his servant Covington collected the finches, and John Gould back in England identified and catalogued them. It’s useful to have smart, industrious friends (and servants)!

Tortoises live mostly on the land, while turtles live in the water. You can immediately see the differences; tortoises have short stumpy legs, for walking, while turtles have flipper/paddle limbs for swimming. It’s the turtles’ bad luck that they still have to struggle out of water up onto land to lay their eggs when they breed — no mean feat!

Attenborough’s book next has a chapter on crocodiles (lower teeth are visible when the mouth is closed) and alligators (lower teeth are invisible when the mouth is closed). Apparently their teeth are good for gripping prey, but not sharp enough to cut it into bites, so they rip by spinning their bodies around the (dead) prey, then have to rise up above the water to swallow the meat, because they “have no lips” to keep water out of their stomachs if they swallow. It’s amazing they ever get anything eaten.

Finally, crocodiles have very long courtship and mating processes, which often involve blowing bubbles at each other to indicate interest.

What a great book! Next up are the lizards, my favorite.

(Other things I learned from “Life in Cold Blood” by David Attenborough: Amphibians and their alien adaptations)

There is a female frog that swallows its eggs to protect them from predators until they mature. Once swallowed, the eggs secrete a substance that inhibits the production of hydrochloric acid in the frog’s stomach and halts normal muscular contraction that shifts food through the stomach and into the gut. Effectively, the frog’s digestive system turns off for six weeks for this “gastric pregnancy”. Not only that, the baby frogs get so big that they compress the female frog’s lungs, and for the last part of this experience she has to breathe through her skin instead. Imagine her relief when the frogs finally emerge from her mouth. (Photo by Mike Tyler)

This and other ultra-fascinating facts are to be found in David Attenborough’s book, “Life in Cold Blood.” I’ve only read the first chapter (on amphibians) so far, and literally every page has some interesting new fact on it. Not only that, but it is chock-full of gorgeous pictures of the animals being described. They’re all so interesting and alien that I’m nearly moved to get an aquarium and populate it for the observational opportunities.

Did you know?

• Some fish (e.g., lungfish) have primitive lungs (simple pouches lined with blood vessels) and can breathe air.
• The great crested newt lives out of the water, in damp regions, returning to the water to breed. Their eggs lack pigment to protect them from UV, so the female individually wraps each egg in a plant leaf with her hind legs (she lays 2-3 every day from March until mid-July! Talk about unending labor!).
• Many salamanders in the northeastern US have lost their lungs and breathe entirely through their skin, developing long tails that increase their surface area relative to their volume.
• Caecilians somewhat physically resemble earthworms, though they are amphibians. They burrow, and they’ve become sightless, although they do still have eyes — they’re just covered by skin. They are carnivorous, and in some species the female rears her young by repeatedly growing an outer skin, letting them nibble it off, and then resting and regrowing the skin. You can actually watch a video of this from the BBC’s Life in Cold Blood show. Wow, they’re tough! (Never go in against a Caecilian…)
• Different frog species may only be able to hear certain frequencies, which correspond to their own vocal range, so that they need not be confused by the cacophony of other species.
• The transformation from tadpole to frog is, really, simply miraculous. It is an herbivore as a tadpole, with a long coiled gut to permit digestion of plant matter. It grows front legs inside its gill chamber which then burst out fully formed on the sides, it develops lungs, its gut shortens and it becomes a carnivore. It basically completely reconfigures itself for an adult life in an alien environment, with alien food and a different means of mobility required.

I’m even more in awe, at the diversity and innovation of life on our one single planet, than I was before opening this book.

Yesterday, I attended the first day of the Astrobiology Science Conference, or AbSciCon. The day began with a great talk by Lord Martin Rees, who is the Astronomer Royal in England. He wrote a book called “Just Six Numbers” about six parameters of our solar system and Earth that have allowed for conditions conducive to the existence of life (and human beings). He was introduced by Paul Davies, who wrote “The Goldilocks Enigma”. Both books are now candidates for inclusion in my to-read list.

I next attended some talks about the galactic habitable zone. While I’ve read about the “habitable zone” inside our solar system (largely determined by the temperature range within which water exists as a liquid), this was the first time I’d encountered its galactic counterpart. In the galaxy, the constraints relevant for habitability (specifically, the creation of planets) involve the probability of a nearby, disruptive, supernova (so you don’t want to be too close to the galactic center, where stellar density is high) and the availability of metals for forming planets, which are more available where stellar density is high since they’re created by stars (so you don’t want to be too far away from the core). Our Sun is at 8.5 kiloparsecs from the galactic center, although it apparently wobbles in and out a bit, and there’s enough uncertainty in the measurement that it’s more like 7.5 to 8.8 kpc.

The discovery of exoplanets (planets outside our solar system, orbiting other stars) is, in my opinion, one of the foremost scientific discoveries of the past decade or so. It sounds like science fiction, but it’s real (we’re up to 287 exoplanets so far!). So far we’ve predominantly found only Jupiter-sized planets that are close to their host stars (and very, very hot), but most expect that this is because those are the planets that are easiest to detect. The hunt is on for Earth-sized planets that reside in their star’s habitability zone. In particular, a five-year study is beginning to collect 100,000 observations of Alpha Centauri B in hopes of detecting terrestrial planets. No planets have yet been detected in the complex (triple star!) Alpha Centauri system. However, in planet formation simulations, 42% of the Earth-sized planets that formed fell into the habitable zone around Alpha Centauri B. Therefore, if there are planets there, they might be very interesting to study (and much closer than many of the other stellar systems with planets). There are also reasons that planets in a binary or triple star system would be less likely to exist (e.g., gravitational disruptions could prevent them from accreting), but it seems like a good place to look.

But maybe our own location isn’t always so habitable, either. It’s been observed that if you plot the number of extant species as a function of time on Earth (a biodiversity curve), there is a certain cyclicity to the peaks and troughs. Fourier analysis identifies frequencies that have a strong correlation with the signal. It was previously thought that there was a 26-27 Myr periodicity, but this is now viewed as an artifact of the sampling rate (through time) of the curve. After the recent revision of the geological time scale, a stronger signal is found with a period of 62 Myr. So, what might be happening to cause biodiversity to peak and fall every 62 Myr? There are a lot of ideas, including the Nemesis theory of a companion star repeatedly passing through and disrupting the solar system, a sharp increase in the number of mantle plumes in the Earth, solar nuclear oscillations, and, intriguingly, oscillations in the position of the solar system with respect to the galactic plane. We seem to rise up (“north”) of the galactic plane and dip down (“south”) with a period of about 64 Myr, which could be a potential match. When we head north, we move in “front” of the galaxy as it travels through the intergalactic medium, exposing us to more of the incoming cosmic rays, which are known to have negative effects on life. Three of the five known mass extinctions in history coincide with a peak of this vertical oscillation (one is already quite firmly believed to have been caused by a meteor impact and therefore need not fit with the cosmic ray periodicity). A less exotic explanation for the cyclicity is that sea level changes have affected how well fossils are preserved, therefore making it appear that there are fewer of them when preservation rates are low. In fact, strontium isotope ratios, which indicate the degree of rock weathering and erosion going on, seem to have a strong 59 My periodicity. I’d say that the jury’s still out on this one.

Last night, I spent a fun evening playing board games (new: Container!) and engaging in geek talk. Oh, how I love a good intellectual discussion! (You know, like the Salon des Geeks.) I guess it’s the geek version of a jam session; everyone hangs around and throws in their particular views or brings up new themes as the thought strikes them. Here’s what the idea buffet served up last night:

According to the latest evidence, Homo sapiens apparently did not evolve from Homo erectus. Both of us, plus Homo habilis, came from a common ancestor — erectus and habilis were different (less successful) offshoots.

There’s an anti-aging chemical that reverses effects such as a loss of elasticity in connective tissue which has been doing human studies since 2001 (and shown that it helps with, for example, hardening of arteries). However, the chemical’s patent expired, so it is now in the public domain, and no pharmaceutical company therefore is interested in finishing the (expensive) trials needed to get it FDA-certified.

I claimed that irradiated food seems to be unavailable because people are scared of the word “irradiated” and therefore wouldn’t buy it. Others noted that irradiated food can actually have a bad taste, since the irradiation process can damage the “good” proteins in, say, milk, not just the “bad” (bacterial) ones. So there might be a valid taste-reason that irradiated milk is inferior to un-irradiated (bacteria-laden) milk. Also, apparently many people agree with this statement: “If you had some radioactive milk, boiling it would make it safe to drink.”

As annoying as shopping is, it can be viewed in a more positive light if you think of it as an act of exercising your financial power. I like that.

And to follow up on my comment about carbonated fruit, there is actually a company, Fizzy Fruit, that is marketing it.

There was much more, and it got very late, and it was a great evening overall.