RSS

Tag Archives: earth

Life on Mars

I’m going to go out on a limb here:

With the recent discovery of (evidence for) liquid water on the surface of Mars, there’s going to be life there.

My own personal hypothesis would be that it’s either going to be terrestrial life that was transported to Mars via rock ejected from Earth by the impact of past meteors or the other way around, an idea known as panspermia. One solid possibility would be Earth –> Mars via ejecta following the Chicxulub asteroid impact in Mexico. It is commonly thought that Mars may have been a much more hospitable place long ago, including large seas suggested by potassium-thorium-iron enriched areas visible by Gamma Ray Spectrometer. This enrichment may be explained as an accumulation deposited by liquid water on the surface of the planet.

A superimposition of gamma-ray data from Mars Odyssey's Gamma-Ray Spectrometer onto topographic data from the laser altimeter onboard the Mars Global Surveyor.

A superimposition of gamma-ray data from Mars Odyssey’s Gamma-Ray Spectrometer onto topographic data from the laser altimeter onboard the Mars Global Surveyor.

If this is correct, some residual bacteria-like organisms remaining from a more biotic history could have seeded Earth in a Chicxulub-like impact of Mars.

“Tetsuya Hara, et al, at Kyoto Sangyo University in Japan have calculated that a large amount of Earth landed on the Moon and Mars, but also on other planets that may be compatible with life—the Jovian moon, Europa, the Saturnian moon, Enceladus, and more surprisingly even planets like Earth orbiting other stars.” (from askwhy)

On porrible map of Chicxulub asteroid ejecta

On possible map of Chicxulub asteroid ejecta

Regardless of any relationship between the life of the two planets, I have to say that I’m firmly on the side of manifest destiny here. I completely understand the arguments against contaminating another planet with life from this one, but I don’t imagine a future without Earthlings spreading to the other planets of this solar system.

Without the need to transport masses of water, NASA (and other Terrestrial space agencies) may suddenly see a manned mission to Mars as imminently do-able. The question changes from could we go to should we go? What are our obligations if our presence there will disturb an extant biosystem?

Carl Sagan said “no.” It was his belief that any planet with indigenous life should be protected from human intrusion. Perhaps an inspiration for Star Trek’s Prime Directive.

On this issue, I would have to part with Sagan’s advice – perhaps on purely selfish grounds. I want humans to explore the heavens and I believe that a strict policy like this Prime Directive would prevent that forever.

If you are reading this, take a moment contribute your two bits.

If possible, should humans go to and possibly remain, on Mars?

 
Leave a comment

Posted by on September 29, 2015 in Uncategorized

 

Tags: , , , , , , ,

“Life is nothing but an electron looking for a place to rest”

ImagePhysics -> Chemistry -> Biology

The Smithsonian Magazine has an article this week proposing that we consider Mars as the origin of Terrestrial Life. This notion stems from Steven Benner’s Four Paradoxes: The Tar Paradox, The Water Paradox, The Single Biopolymer Paradox and The Probability Paradox. Each of these is described in the abstract of his work, and do add up to a possible alternative for life’s origin. However, as compelling as his arguments may be, the origin of life will always be a mystery veiled in time. Even if we were to find evidence of life on Mars that is very much like that on Earth, it would be difficult to say whether Terrestrial life was the origin of Martian life, or vice versa.

Another problem I have with tracing the origins of life off-planet is that it does not solve anything, but merely relocates the source. So it’s not that I feel that Benner’s work is uninteresting or unworthy of consideration, but presently, Ockham’s razor precludes Imageseriously considering extra-terrestrial origins without a good deal more hard evidence. Further,  relocating the source or life’s origin does little to change how we think about  origins. Regardless or where life started, it is still highly probably that it began with RNA, a unique molecule in that even today it serves dual roles as an information-carrying molecule and a structural one that often has enzymatic function. And, that the addition of the more stable , DNA molecule as the primary source of information happened later – as adding protein synthesis also did for providing an alternative structural / functional molecule. 

Evolution of the Central Dogma?

                                                              RNA

                        DNA -> RNA                                                  RNA -> Protein

                                                  DNA -> RNA -> Protein

 
4 Comments

Posted by on August 31, 2013 in Uncategorized

 

Tags: , , , , , , , , , , , ,

Radiometric dating

Image

An old Rock

My General Biology class is discussing means by which we can date objects. This comes from a question by Ernst Mayr, “What kind of world do we live in?” The basis of this question is, how old is the planet? and how constant is it?

In biology these questions have notable importance because how we explain life’s processes requires that we know how much time these processes are operating over. One would be limited in their explanation of life if we know the world to be young – say, only 1 million years old. Whereas, the current estimate of 4.5 billion years, including ~3.5 billion years with life of some kind, allows for much slower processes to operate.

I discussed one of these measurements, radiometric dating, in an earlier post.  Take a look at how this is done and be sure that you understand the practice problem presented and can work out a similar problem on your own for the quiz.

 
Leave a comment

Posted by on April 9, 2013 in Uncategorized

 

Tags: , , , , , , , , , ,

New (to me) Podcast

ImageI just discovered a podcast that I thought some of you might be interested. It’s called paleocast and can be found at:

http://www.palaeocast.com

Check it out and let me know what your thoughts are on their work.

 
Leave a comment

Posted by on March 25, 2013 in Uncategorized

 

Tags: , , , , ,

What kind of planet do we live on?

This is the last week of my Fall 2012 General Biology class and we have finally gotten to the material I look forward to all year.

Throughout the semester we build towards an understanding of the central dogma (DNA –> RNA –> Protein). Early on we are introduced to this idea and are given the basics that DNA is the information that is required to build cells; which are made of these proteins as well as some other biomolecules. It’s easy to have a protein-centric view of the cell because these molecules provide structure to the cell and accomplish many of the functions of the cell by acting as receptors, enzymes, signaling molecules, etc. (This is an over-simplification, but one I can live with)

Last week we focused on the details of transcription and translation and how these molecular processes read information from DNA to make an mRNA ‘message’ that leaves the nucleus and goes to the cytoplasm where translation of this message results in the production of a protein with the specified amino acid (AA) sequence.

This segued into what happens when there are errors or mutations along the way. Because the AA sequence of the protein is determined directly from what is encoded in the DNA, changes is DNA may have direct consequences on the protein. Another central idea I teach is ‘Form Dictates Function.’ Because the form of a protein is determined by the AA sequence, changes in sequence mean changes in form and therefore changes in function.

So, how does this relate to my opening question, ‘What kind of planet do we live on?’

A Molecular View of The Central Dogma

A Molecular View of The Central Dogma

The process illustrated by the central dogma is fairly faithful. Most often the proteins are NOT mutated and are made just as the DNA directs and they function as expected. However, once in a while, mutations come in and hit the DNA and there is suddenly a DNA change leads to a change in the RNA, that leads to a change in the AA sequence, that leads to a new folding of the protein. This may provide a benefit (very rarely) or may cause a problem (more commonly). If it confers a benefit, this provides an advantage to the bearer of these new proteins and they may be more successful living longer and leaving more children. If it is detrimental, then the bearer may not live as long and may have few, if any, children.

But this is a SLOW process.

If the world was 4000 years old, this process could not conceivably explain the diversity of life on Earth. But if the world is 4.5 BILLION years old, that may be enough time. Darwin struggled with this idea and it was not until he witnessed the wide world during his voyage aboard the HMS Beagle that he started to see evidence that the world was much older than he once suspected.

Andean Fossils

Marine Fossils from the Andean Mountains – Similar to what Darwin found in the same place.

One of the first suggestions that Darwin say about the history of the Earth was the presence of sea fossils high in the Andes Mountains. How could this be? These could only make sense if the mountains were not always mountains, but the Earth changed over time.

With the idea of ‘deep time’, meaning that the Earth is very, very old – on the order of Billions of years – Darwin’s idea of mutations accumulating over time as fuel for evolution becomes plausible.

What kind of planet do we live on?

A very old , changing planet

 
Leave a comment

Posted by on December 4, 2012 in Uncategorized

 

Tags: , , , , , , , ,

First on Land

I found this video on the Ted-ed Site. Since my class is currently reading Your Inner Fish, the story about how the first animals that are direct ancestors of mammals came out of the water, I thought this video on the very first animals to come out of the sea was very appropriate.

Have a look at the video and check out the questions afterwards… you never know, one might show up as extra credit on a quiz…

http://ed.ted.com/on/wAFSbjQj

I hope you enjoy.

 
Leave a comment

Posted by on November 14, 2012 in Uncategorized

 

Tags: , , , , , , ,

RadioLab’s ‘What the Slinky knows’

My son and I were listening to RadioLab in the car – as we often do -and heard an interesting short on ‘What the Slinky knows‘. What an interesting podcast. Check out the attached video of the point in question. Here we see a slinky being held up at the top, but allowed to dangle until it settles and becomes still. At this point, the top is released, but the bottom doesn’t move:

The question posed in the podcast is: Why does the bottom of the slinky seem to levitate until the top reaches it and then the whole things begins to move together. The basic question is relatively simple if you think about the situation and model all the forces in operation (1. gravity – down; 2. 3. hand holding slinky-up; force of the spring’s tension – up.)

When the slinky is released, you eliminate force #2, leaving only #1 and #3 in operation. The interesting thing is that force #3 will continue to operate and pull up until the top of the slinky collapses on itself and then only force #1 remains.

But then Neil DeGrass Tyson was brought into the discussion and said something I didn’t expect. He started with what you might expect him to comment on – an immediate application to space, which seems completely appropriate. His example was about the sun. Given that the sun is several light minutes away from the Earth (just over 8 minutes), if the sun were to somehow disappear, we wouldn’t know for those intervening eight minutes.

During that time, we would be seeing light that had left the sun eight minutes earlier and everything would look fine. Then, at the 8:20 mark (give or take), we would finally see that the sun had gone missing….

…. and here’s the good part: He also said that it wouldn’t be until then that the Earth would be released from its gravitational attraction to the sun and go flying off at a tangent into space. This begs a question that I don’t know the answer to: what is the ‘speed of gravity’? Would it take eight minutes for the Earth to be released and go tumbling into space… or does gravitational attraction operate at a different speed than light?

I’m serious, I don’t know the answer – and even more frustrating, I don’t know how this question could even be asked. I’m all ears for the answer to this one.

 
Leave a comment

Posted by on September 16, 2012 in Uncategorized

 

Tags: , , , , , , , , ,