Tuesday, September 29, 2015

How about that water on Mars?

NASA announced a big press conference over the weekend about the planet Mars, and I took time out of Algebra II yesterday to watch it with my students.  As most people expected, they announced evidence of liquid water on Mars.  So what's the big deal?

For some time now, scientists have observed seasonal streaking on slopes on Mars.  You can see some of the streaks in the image above (courtesy NASA/JPL/University of Arizona).  They've been called RSL, which stands for Recurring Slope Lineae, which means, "lines that appear repeatedly on slopes."  That certainly seems like the action of some kind of liquid running down the slope making the surface appear darker.

But wait, Mars is farther from the sun that we are, about 48 million miles farther than earth on average.  That makes Mars much colder than earth.  According to Space.com, the average temperature on Mars is -80 degrees F.  During the summer, some spots on the equator can get up to 70 degrees F, but at night the temperature can still drop to 100 below.  How could there be liquid water under those circumstances?  Wouldn't the water be frozen, except for those brief warm days on the equator?

Well, if you remember back to your general chemistry days (if you took general chemistry), you might recall a thing called "freezing point depression."  When you add salt to water, the freezing point goes down (and the boiling point goes up).  That means you can have liquid water at temperatures colder than the normal freezing point of water.  Is that what's happening on Mars?

NASA scientists and collaborators pointed an orbital spectrophotometer at the RSLs.  A spectrophotometer is an instrument that can detect the presence of all sorts of chemicals, and the one they used is on a satellite orbiting Mars.  When they measured the RSLs directly, they found evidence of salt water, but when the RSLs were gone (during the Martian winter), there was no evidence of salt water.  The salt they found was a chemical called perchlorate, which apparently can lower the freezing point of water quite a bit.

So there you have it, folks, liquid water on Mars.  What does it matter?  Well, you'll notice in the press release that they make a big deal about life on Mars, which has an interesting connection to origins.  Here's how the reasoning goes: If you think that there is a natural explanation of where life came from in the first place, then you will not be satisfied with explaining life by claiming that God created it.  Instead, you'll want to figure out how it could have happened, whether or not God was involved.  But you also notice that life is amazing and complex, and it seems unlikely that it would just happen.  This leads you to suspect that life "emerges" (whatever that entails) when the conditions are right.  So if you can find life on Mars, that makes the second option seem more credible.  Finding life on Mars would make life on earth seem less spectacular and unique and more of a natural consequence of having a particular sort of planetary system.

Liquid water factors into this because liquid water is required for life as we know it.  Finding water on Mars makes it at least plausible that life of some sort could exist there, although perchlorate brine is not something I would think of as favorable to life.  Let's be very careful about this hype though:  Finding liquid water on Mars does not change the probability that we will find Martian life.  Liquid water makes it more plausible or possible that life could exist there, but plausibility does not mean probability.  All kinds of crazy things are possible, but that doesn't make them likely.

As for me, I think water on Mars is neat, and if there were genuine Martian microbes, that would be neat too.  Since I already know that God created life, discovering life on Mars wouldn't really change anything I believe about origins.

Ojha et al. 2015. Spectral evidence for hydrated salts in recurring slope lineae on Mars. Nature Geoscience doi:10.1038/ngeo2546.

Feedback? Email me at toddcharleswood [at] gmail [dot] com. If you enjoyed this article, please consider a contribution to Core Academy of Science. Thank you.

Tuesday, September 22, 2015

Figuring out Homo naledi

Homo naledi has been a delightful development in my life, and I had nothing to do with the actual research.  I just got up one morning and found two emails from some very early risers who had already read the press coverage.  That derailed my whole day's work as I concentrated on better understanding what exactly Homo naledi was and what it might mean for my understanding of creation.  Few things get me more wound up than new hominin fossils.

As you might expect, though, there have been some folks happy to use Homo naledi as yet another opportunity to mock creationists.  It's tiresome, but it comes with the territory.  Apparently, because creationists disagree about the significance of Homo naledi (and specifically about whether or not it's human), we're stupid, anti-scientists, clueless, whatever.  Of course, I could reverse that opinion, since there's not a lot of agreement on just what Homo naledi means for human evolution.  What's good for the goose is good for the gander, but that really would be stupid to claim that people are stupid just because they don't agree about something.

Normally, I don't like to pay much attention to insults, but the story going around is that I don't know what Homo naledi is.  Specifically, my hesitance to speak publicly and declare Homo naledi an ape (or a human) has been interpreted as uncertainty.  I want to publicly clarify that I'm not uncertain at all.  Actually, since the first day I heard about Homo naledi, I've been quite confident about what H. naledi is, and I'm mighty tempted to put my opinion right here and take my stand with the other creationists who have declared their opinions.

But the reality is that there are larger issues here.  Many of my readers know that the "historical Adam" has become a debate in evangelical Christianity.  There are some scholars calling us to abandon traditional belief in a real Adam and Eve and instead adjust our theology to do without such characters.  As you might imagine, I don't agree with such things, but I think that the question of the historical Adam is just a superficial issue on top of much bigger problems.  Questions about worldview, science and faith, and evolution in general form an important context within which we pursue answers to questions about the historical Adam and Homo naledi.  To strip questions like "Was Adam a real person?" or "Is Homo naledi just an ape?" out of the larger context is to do a great injustice to scholarship as a whole.  The average churchgoer just wants easy answers, but the reality is that easy answers aren't very easy to come by.  Answering questions about Adam and Homo naledi takes a lot of effort, and what you think about those answers will depend greatly on other questions that might seem unrelated until you start digging into the issues.

So I've got bigger fish to fry here.  I'm not interested in giving some knee-jerk response to naledi.  I'd much rather consider and re-consider my own conviction about naledi.  I want to consult others who know more about subjects that I don't (like geology and theology).  I want to consider other sorts of data than the type I usually focus on.  Unfortunately, that means I don't get to share what I think right away, but that's an important lesson.  We as a church need to become more comfortable with the discomfort of not knowing things right away.  Answers are not easy, and we need to understand that.

If Homo naledi can help teach us patience and longsuffering, then God bless Homo naledi.

(Photo is courtesy University of Witwatersrand)

Feedback? Email me at toddcharleswood [at] gmail [dot] com. If you enjoyed this article, please consider a contribution to Core Academy of Science. Thank you.

Wednesday, September 16, 2015

Dawn of Humanity or Dawn of Recovery?

Tonight on PBS, you can watch the latest NOVA/National Geographic co-production, Dawn of Humanity, focusing primarily on the Homo naledi discovery.  Or you can visit the NOVA website to stream it right now, or you can get it on Amazon and stream it there.

I just wanted to share a few thoughts about the special, because the film stirred up all sorts of excitement in me (again).  First of all, a disclaimer is in order: this movie is thoroughly, unabashedly evolutionary.  I know that should go without saying, but I continue to be surprised by folks who are surprised by how conventional science is so thoroughly evolutionary.  Newsflash: These fossils are interpreted in terms of human evolution on this program.  Human evolution means ape-like creatures evolving into human-like creatures.  Don't expect anything better than that.

Second, this film really communicates the thrill of discovery.  Key points in the discovery and excavation were filmed from the beginning.  We get to see footage of the first two guys going into the cave and finding the bones.  We get to see fossils being unwrapped and declared, "It's Homo!"  We even see the tears of joy in the eyes of one of the young scientists as she watches these discoveries unfolding right in front of her.  Even though I don't think they're right about their evolutionary conclusions, I can relate to the thrill they feel.

Third, we get a look at a body reconstruction of Homo naledi, and they look really weird.  Here is a still from the special that I grabbed.  It's copyright NOVA/National Geographic and whatever researcher made it (and if some official person wants me to take it down, say the word, and it's gone).

On first glance, it's the limb proportions that jump out at me.  Those gangly arms hang all the way down to the knees!  What kind of a creature was this?

Now if you're a young-age creationist, you might be wondering what to make of all this.  The best I can tell you right now is to think of this as something that lived after the Flood, in the wreckage of a world struggling to recover from the worst disaster in history.  Life was not easy for these creatures that God made, whatever they were.

Creationists also might like to read about other creationist reactions.  AIG's Elizabeth Mitchell downplays the evidence of burial and argues that the fossils are not human.  Paleontologist Kurt Wise thinks otherwise, as he shares in this World magazine article.  In the same article, old earth creationist Fuz Rana of Reasons to Believe sides with Mitchell and claims H. naledi is not human (no surprise there).  ICR's Frank Sherwin cautiously suggests it might be human (UPDATE: Someone at ICR has updated the page with a cryptic bit about primate characteristics and shortcomings of the burial interpretation, and it's not clear if Sherwin would continue to stand behind his initial impression).  Ken Ham wisely notes that creationists will likely disagree on Homo naledi because of the fragmentary nature of the fossils and our limited ability to examine the fossils firsthand.

However this turns out, I would like to publicly thank God for putting me here at this point in history.  Within three months, I've seen high resolution images of the surface of Pluto and now Homo naledi.  As a kid growing up in the 80s, I could only imagine such wonders, and God gave me life and eyes to see them!

How great thou art!

Feedback? Email me at toddcharleswood [at] gmail [dot] com. If you enjoyed this article, please consider a contribution to Core Academy of Science. Thank you.

Friday, September 11, 2015

What can we learn about Homo naledi?

I've had a day to digest the publications about Homo naledi, and I'm still just as excited as I was yesterday.  There are at least twelve other people in the world almost as excited as I am, since I told them yesterday to do homework because there are some things in this world more important than algebra.

I'm currently writing up my results, but unfortunately for you, I won't be spoiling them here.  I'm a firm believer in peer review to make sure I've done my due diligence.  I will be submitting my manuscript for formal publication in a journal, and until then, I'm going to keep a lid on things.  In the mean time, though, I wanted to offer a few additional thoughts.

First a reader question: Could these be antediluvian (pre-Flood)?  I doubt it.  The Rising Star Cave where these fossils were found is in a very old dolomite (Monte Christo Formation), possibly pre-Flood, but that doesn't tell us when the cave itself was carved.  I would not expect a cave like this, with an opening to the surface, to survive the Flood as intact as it is.  This looks more like a post-Flood accumulation of bones.  Finally, all hominin fossils previously known are considered post-Flood by most of the creationists that should know about these sorts of things.  So I'm working under the assumption that these are post-Flood fossils, until someone gives a very good argument otherwise.

Next, I wonder what can we learn about human history from this discovery?  On the one hand, reporters occasionally overhype discoveries like this.  A classic example is the hysteria over Ida.  This time, things are different.  This is legitimately a very, very exciting discovery, and I don't hear anyone claiming that this will change everything.  Smithsonian magazine says it "may change what we know about human evolution," and National Geographic says that it "changes the human story. But how?"  It's like everyone's being extra careful after the backlash from Ida.

If Homo naledi doesn't change everything, then does it change anything?  Let's think about this from a creationist perspective (since that's the framework I'm most interested in.)  Can we learn anything about the human story from Homo naledi?  Honestly, I think it's too soon to say for sure.

IF H. naledi turns out to be nonhuman, then we don't learn much at all about human history from it.  It's just not human.  But...

IF H. naledi turns out to be human, we might learn something new about human history.  Back in the early nineties, when I first got a copy of Marvin Lubenow's Bones of Contention, the fossil hominin story was fairly straightforward.  There were taxa that looked very human.  Homo erectus and Neandertals from the neck down look very similar to us.  They're as tall as us and clearly walk around upright.  There was no question in my mind that they were human.  Then there were the australopiths, which were very different from us and therefore not human.  That also seemed "obvious."  Other taxa like Homo habilis and Homo rudolfensis seemed like they were too fragmentary to have a definitive opinion about.  So I was happy.  Aside from a few skulls, fossil hominins seemed like a clear case of these-are-human and those-are-not.

Over the past twenty years, however, things have gotten progressively more complicated.  We've seen multiple new australopiths and other hominins that have raised some interesting questions about humanity.  I'm thinking especially about the discoveries at Dmanisi, where we have what appear to be Neandertal, H. erectus, and something even more "primitive" living side by side.  Dmanisi suggests to me that we creationists have severely underestimated the possible variability of humanity.  In a sense, we've been "tricked" by the homogeneous sameness of living humans.

Dmanisi also excites me because it's right in the region where the "mountains of Ararat" are supposed to be.  OK, it's not exactly there, but given the global geography of Homo erectus and Homo ergaster discoveries, it's remarkably close.  So if Noah and co. were coming off the Ark, and their children were starting to look a little "different," wouldn't you expect that a population like the Dmanisi hominins would exist?  I sure would.

Add to that my infamous judgment about Australopithecus sediba.  I was actually finishing a paper on hominin fossils in 2010 when A. sediba was announced, and that gave me an opportunity to test my results:  Would A. sediba group with one of the existing groups I had discovered?  Or would it collapse the groups into a single group (as evolutionists would suggest)?  Yes, it grouped; no, it did not collapse the groups into one.  The only "problem" (for some commentators) was that I put A. sediba in the human group, when to a lot of creationists it was "obviously" not human.

Let's not forget the most important discovery from that study, though: Homo and Australopithecus did not just blend together into a single group.  I did not find an unbroken line from nonhuman ape to human.  I found, as creationists have always claimed, that there were two separate groups: one of which contains Homo sapiens, Neandertals, and H. erectus (human descendants of Adam and Eve), and the other contains nonhuman ape-like creatures like Australopithecus afarensis.  As I think back over the dramatic advances in paleoanthropology since Lubenow's book first appeared, this result seemed like something very worth celebrating.  It's too bad people freaked out about A. sediba and lost sight of the more important result.

Revisiting that research is yet another reason why Homo naledi has me really excited.  Here again, like A. sediba, we have a South African hominin with a very weird mix of traits and a skull that looks very "primitive."  But this time, we also have a very interesting argument that these individuals were deliberately buried.  Creationists have long considered burial as a sign of humanity, so what will this do to the argument?  What will my baraminology study tell me about Homo naledi?  How will H. naledi change our opinion of A. sediba?  What will creationists learn about the human story from Homo naledi?

I can't wait to find out!

Photo of Homo naledi hand courtesy of the University of Witwatersrand.

Feedback? Email me at toddcharleswood [at] gmail [dot] com. If you enjoyed this article, please consider a contribution to Core Academy of Science. Thank you.

Thursday, September 10, 2015

Astonishing fossil find in South Africa: Homo naledi

Wow, I'm kind of shell shocked this morning after receiving word of the richest hominin fossil discovery in Africa.  Lee Berger (discoverer of Australopithecus sediba - the fossil that got me into so much trouble five years ago) is back with a new fossil he calls Homo naledi.  The remains of Homo naledi were found in the "Cradle of Humankind" world heritage site, about 30 miles northwest of downtown Johannesburg. The thing that makes this discovery special is the sheer quantity of material: Two excavations in 2013 and 2014 recovered more than 1500 individual bone pieces, about half of which can be diagnosed to the skeletal element.  Check out the picture below (and if you're a nerd like me, hold onto your jaw, because it's going to drop).

That's a lot of bones.  They apparently have every life stage from infant to elderly in this assemblage.  The bones come from cave floor sediments in the Rising Star Cave system, and the researchers suggest that the bones are from a burial site.  Till now, burial was only known (I think) in Homo sapiens and Neandertals.  The place the bones were found basically has nothing but Homo naledi remains except for a few rodents and birds not directly associated with the H. naledi material.  There is no evidence on the bones that they accumulated in the cave because of cannibalism or carnivory (the bones haven't been gnawed on).  There is also no evidence that the cave was ever occupied by these hominins.  So there's hundreds of hominin bones in a single location without any evidence that they were killed and eaten.  That suggests that the easiest explanation for their presence in the cave is burial.

What do they look like?  They're kind of short with small skulls.  In height, they were within the range of Homo erectus, averaging around 4 ft or so.  That's taller than the average Australopithecus, but it's a bit shorter than modern humans.  The cranium, however, is much smaller than erectus (and substantially smaller than Homo sapiens).  The feet and legs look remarkably human, and the hands are a bit weird.  They evidently have curved fingers like australopiths, but the palm is more like modern humans.  The hands are definitely not crazy long like Ardipithecus.

Where does this leave me as a creationist?  As usual, I'm reserving judgment until I've had time to look over the research papers and carefully consider the results.  I'm kind of biased towards concluding that H. naledi is human (as in descended from Adam and Eve), mostly because the evidence for intentional burial really impresses me.  Also, the anatomy of the legs and feet are also surprisingly human.  I could be wrong, of course, which is why I'm not going to make some hasty and inappropriately definitive judgment.  In other words, I'm not going to shoot my mouth off.

As for other creationist organizations, I'm not entirely sure how they will react.  Given that Hugh Ross only accepts Homo sapiens sapiens as human, Reasons to Believe will certainly judge these remains as nonhuman and probably will dispute the burial hypothesis.  As for the young-age creationist organizations, there will probably be some that side with RTB and dispute the idea that H. naledi was human.  I suspect others (I don't know which) will be impressed with the burial evidence like I am.  I doubt that any will be hesitant in their judgments, though.

While I'm looking at these results more carefully, please peruse the following pages that explain all sorts of cool things about H. naledi.

Berger et al. 2015. Homo naledi, a new species of the genus Homo from the Dinaledi Chamber, South Africa.  eLife 4:e09560.

Dirks et al. 2015. Geological and taphonomic context for the new hominin species Homo naledi from the Dinaledi Chamber, South Africa.  eLife 4:e09561.

University of Witwatersrand Homo naledi press page (with pretty pictures!)

Stay tuned!  This is not my last word on Homo naledi.

The photographs in this article come courtesy of eLife and the University of Witwatersrand.

Feedback? Email me at toddcharleswood [at] gmail [dot] com.  If you enjoyed this article, please consider a contribution to Core Academy of Science.
Thank you.