Today’s New Reason To Believe

Posted by Fazale ‘Fuz’ Rana, Ph.D.

New Discovery Undercuts Origin of Life at Hydrothermal Vents

Most people now recognize that smoking takes years off of one’s life. But if it wasn’t for smokers, life’s start wouldn’t be possible—at least according to some origin-of-life researchers.

One prominent origin-of-life model posits life’s beginnings at deep-sea hydrothermal vents, sometimes referred to as “black smokers.” These structures result when superheated water pushes through the Earth’s crust on the ocean floor to form a sea vent. The water that spews out of the vent is rich in dissolved minerals including sulfides. When the superheated water comes into contact with cold water surrounding the sea vent, it causes the metal sulfides to precipitate. These precipitates look like black smoke emanating from the sea floor. Over time as the sulfides deposit around the vent, a chimney-like structure forms.

A complex, rich ecosystem is associated with black smokers. Some bacteria and archaea thrive near hydrothermal vents. Here the microbes make use of gases like methane and the sulfides through a process called chemosynthesis to generate foodstuff. These chemoautotrophs serve as the primary producers in the hydrothermal vent communities.

Since the discovery of thriving microbial communities near underwater smokestacks, origin-of-life researchers have thought that perhaps life began in similar locales on early Earth. If life can live at hydrothermal vents today, why couldn’t it originate there as well? After all, the microbes thought to be representatives of some of the oldest organisms on Earth are hyperthermophiles and thermophiles, the types of (heat-loving) organisms found at these vents. Additionally, laboratory simulation experiments designed to mimic the chemical and physical conditions of hydrothermal vents have demonstrated that biologically interesting compounds could have been generated in these locales on early Earth. Presumably, these compounds could have formed a complex chemical mix that eventually spawned the first life-forms.

New research, however, indicates that this explanation for the origin of life is probably not correct.

This work took advantage of the typical biochemical makeup of nucleic acids, like DNA and RNA, and proteins of hyperthermophiles and thermophiles to determine (from an evolutionary standpoint) the identity of the last universal common ancestor.

The composition of these important biomolecules serves as a “molecular thermometer” of sorts. For example, hyperthermophiles and thermophiles possess nucleic acids more enriched in guanine and cytosine compared to those of organisms that live at more moderate temperatures. Likewise, the amino acid compositions of thermophilic proteins are depleted within certain amino acids. (For a detailed discussion of the principles behind this analysis go here.)

Using both thermometers, the researchers concluded that the last universal common ancestor must have lived at moderate temperatures. That is, it wasn’t thermophilic. This means that from an evolutionary vantage point, life’s origin probably didn’t take place at hydrothermal vents. (For more information on other problems associated with alternative origin-of-life explanations see Origins of Life.)

It looks like smoking wasn’t all that good for Earth’s first life either.

Posted by Fazale ‘Fuz’ Rana, Ph.D.

New Discovery Affirms RTB Model Predictions

Even though I’m a budget-hotel kinda guy, occasionally I splurge and stay in a really nice place. It’s fun to get a chance to experience firsthand how the “other half” lives.

A recent study of some of the microbes found in Lake Matano (Indonesia), the world’s eighth deepest lake, provides biologists and geologists a first-hand look at how the earliest life on Earth lived. This new insight provides more evidence for RTB’s origin-of-life model.

RTB and Evolutionary Origin-of-Life Models

One of the key points of difference between the RTB and evolutionary models centers on the timing of life’s first appearance on Earth. The RTB scientific creation model, based on Genesis 1:2 and Deuteronomy 32:9-12, predicts that life should appear early in Earth’s history and that the first life-forms should be inherently complex.

Evolutionary origin-of-life models, on the other hand, require a long percolation time, perhaps up to one billion years, before life can emerge from a primordial soup. These naturalistic scenarios also predict that the first life-forms should be relatively simple.

The Scientific Evidence

As described in Origins of Life, geochemical evidence already indicates that life was present remarkably early in Earth’s history, possibly as far back as 3.8+ billion years ago. (Prior to this time, life would have been impossible on Earth, since the planet’s conditions were “hellish” and unsuitable for life.)

Some origin-of-life researchers, however, question the authenticity of these geochemical finds. They maintain that these markers for early life are actually artifacts produced by inorganic processes.

Banded Iron Formation

One potential biomarker under question is banded iron formations (BIFs). These unusual iron ore deposits are found in sedimentary rocks dated older than 1.8 billion years in age. BIFs are most abundant between 1.8 and 2.5 billion years ago, but also exist in rock formations as old as about 3.8 billion years in age.

BIFs consist of alternating layers of chert (silica) and the minerals hematite (Fe²O³) and magnetite (Fe³O⁴). Deposits of this type don’t form today. Geologists believe that BIFs formed at a time in Earth’s history when high levels of dissolved iron (Fe²+) and silica existed in the oceans. The silica deposited in ocean sediments to form the chert layers. Geologists maintain that the iron ore “bands” formed when the dissolved Fe²+ became oxidized to form hematite (Fe²O³) and magnetite (Fe³O⁴).

Most geologists think that BIFs dated between 1.8 and 2.5 billion years ago resulted from biological oxidation when the oxygen generated by cyanobacteria converted Fe²+ to Fe³+

Banded Iron Formations on Early Earth

In other words, BIFs stand as a marker for biological activity. But what about the BIFs deposited in the geological record before that time? Does their presence mean that life existed on Earth as far back as 3.8 billion years ago? Not necessarily, according to some scientists. It’s possible that these BIFs were generated by inorganic oxidation processes or by a UV radiation-driven reaction.

Other researchers have pointed out that the low levels of oxygen on the early Earth make it unlikely that inorganic oxidation could have produced the ancient BIFs. In a similar vein, while scientists have successfully generated BIF-like materials in the lab using UV radiation, it doesn’t seem probable that this process would operate under the complex chemical conditions of the early Earth.

These problems indirectly suggest that biological oxidation accounts for the production of the earliest BIFs on Earth. Still, this explanation comes with challenges. Many origin-of-life researchers tend to doubt if cyanobacteria were present on Earth at 3.8 billion years ago. It’s possible that another group of photosynthetic bacteria (anoxygenic phototrophs) could have produced the BIFs. These bacteria can oxidize Fe²+ to Fe³+ as part of their photosynthetic activity. The issue with this scenario is that these microbes live in highly specialized environments that consist of iron-rich, shallow ephemeral water. These environs are not good analogs to the oceans of the early Earth.

The work of the biologists and geologists on Lake Matano weighs in here. These scientists have just discovered anoxygenic photosynthetic bacteria in Lake Matano that can oxidize Fe²+. This lake closely compares to the most likely conditions for the oceans on early Earth. If photosynthetic bacteria can convert Fe²+ to Fe³+ in Lake Matano, it makes it even more likely that BIFs that date to 3.8 billion years in age are biogenic products generated by bacteria that engage in anoxygenic photosynthesis.

BIFs, along with other biomarkers, collectively indicate that life originated early in Earth’s history as soon as our planet could sustain life. The microbes that generated BIFs must have been metabolically complex, given what we know about the anoxygenic microbes that are capable of phototropically oxidizing Fe²+in Lake Matano.

This new insight adds further support for the RTB origins-of-life model and, at the same time, makes little sense within an evolutionary framework. The sudden appearance of metabolically complex life on Earth comports well with the notion that a Creator intervened to bring about the creation of the first life-forms on Earth.

The accommodations in the Archean oceans for the earliest life on Earth may not meet the four-star quality that many people expect when they stay in a high-end hotel, but it appears to have suited these organisms just fine.

Posted by Fazale ‘Fuz’ Rana, Ph.D.

Discovery of Old Lab Vials Erupts New Interest in a Famous Origin-of-Life Experiment

It never ceases to amaze me what turns up when I clean out our garage: forgotten stuff that brings back memories, and occasionally, old things that still have value.

And this is exactly what some former students and associates of the late origin-of-life researcher Stanley Miller discovered when they cleaned out his lab after his death. Old vials from leftover experiments that bring back memories of his famous spark-discharge experiment may shed valuable new light on how prebiotic materials could have formed on the early Earth.

The Miller-Urey Experiment

Miller’s work, conducted in the early 1950s, was the first experimental validation of the Oparin-Haldane hypothesis. Based on the principles of chemical evolution, this model was one of the first scientific theories to describe a mechanistic pathway between simple chemical compounds and life.

To test this hypothesis Miller filled the confines of a carefully assembled glass apparatus with methane, ammonia, and hydrogen after diligently excluding oxygen from the system. At that time, scientists thought the gases Miller used in his experiment existed in early Earth’s atmosphere. A boiling flask of water connected to the glassware introduced water vapor into the headspace and simulated early Earth’s oceans. Miller passed a continuous electric discharge through the gas mix to simulate lightning. The results showed that the primitive atmosphere of the early Earth could, in principle, generate amino acids, one of the key building blocks of life.

Status of the Miller-Urey Experiment

Today, the Miller-Urey experiment is generally considered to be irrelevant to the origin-of-life question. Current understanding of the composition of early Earth’s atmosphere differs significantly from the thinking of the 1950s. Most planetary scientists now believe the Earth’s primeval atmosphere consisted of carbon dioxide, nitrogen, and water vapor. Laboratory experiments indicate that this gas mixture is incapable of yielding organic materials in Miller-Urey-type experiments.

In May 2003 origin-of-life researchers Jeffrey Bada and Antonio Lazcano, long-time associates of Miller, wrote an essay for Science commemorating the 50th anniversary of the publication of Miller’s initial results. They pointed out that the Miller-Urey experiment has historical significance, but not scientific importance in contemporary origin-of-life thought. Bada and Lazcano wrote:

Is the “prebiotic soup” theory a reasonable explanation for the emergence of life? Contemporary geoscientists tend to doubt that the primitive atmosphere had the highly reducing composition used by Miller in 1953.

In his book Biogenesis, origin-of-life researcher Noam Lahav passes similar judgment:

The prebiotic conditions assumed by Miller and Urey were essentially those of a reducing atmosphere. Under slightly reducing conditions, the Miller-Urey reaction does not produce amino acids, nor does it produce the chemicals that may serve as the predecessors of other important biopolymer building blocks. Thus, by challenging the assumption of a reducing atmosphere, we challenge the very existence of the “prebiotic soup,” with its richness of biologically important organic compounds.

Revived Interest in Miller’s Experiment

By sifting through the items left behind in Stanley Miller’s laboratory, his former students and associates uncovered vials of material from his original experiments that they think gives new importance to the Miller-Urey experiment.

Miller actually performed three versions of the spark-discharge experiment. All three permutations yielded amino acids and other organic compounds. Miller decided to focus his efforts, however, on the version that now appears in biology textbooks because he thought that it most closely modeled the atmosphere of early Earth.

Still, Miller held on to cartons of vials containing materials from the other two variations of the spark-discharge experiment along with notebooks that carefully documented the experimental work he performed.

After stumbling upon the vials and corresponding notebooks, Miller’s colleagues decided to re-analyze their contents using state-of-the-art analytical methods not available to Miller fifty years ago.

To their surprise, Miller’s associates discovered that the “textbook” version of the Miller-Urey experiment wasn’t the most successful. The most productive synthesis was one that introduced water into the headspace as a fine mist using an aspirator. This particular experimental rig produced more amino acids with a greater chemical diversity than the textbook experiment.

The design of this forgotten experiment intrigued Miller’s collaborators because it models volcanic emissions that could have occurred on early Earth. Accordingly, volcanic lightning would have served as the energy source that generated prebiotic compounds as it passed through volcanic gases and steam—assuming that the volcanic emissions on early Earth consisted of reducing gases.

Miller’s cohorts now argue that this re-discovery gives new relevance to Miller’s old experiment. Perhaps the sources of prebiotic materials on early Earth were volcanic emissions, not chemical reactions taking place in the atmosphere.

Were Volcanoes the Source of Prebiotic Compounds?

The proposal by Miller’s former associates is not the first time that origin-of-life researchers have appealed to volcanoes as the source of prebiotic compounds. As Hugh Ross and I describe in our book Origins of Life, other scientists have suggested this possibility.

Based on the chemical composition of volcanic emissions today, there doesn’t seem to be much hope that prebiotic materials could form in this environment. The gases spewing from volcanoes today consist primarily of water, carbon dioxide, and sulfur dioxide. This is a highly oxidizing mixture of gases that will not generate prebiotic materials in laboratory simulation experiments like the ones that Miller performed.

But were the gaseous emissions of volcanoes on early Earth different? Did they consist of gases like the ones used by Miller in his spark-discharge experiments? Research conducted a few years ago indicates the opposite. It appears as if the gaseous emissions of volcanoes 3.9 billion years ago were identical to the emissions today. This result means that the conditions of Miller’s experiment were not relevant for either the atmosphere of the early Earth or volcanic environments at that time.

Miller’s work and his status as a scientist remain fixed in a prominent place in the history of science. However, perhaps it’s best that Miller’s vials are removed from the lab once and for all, and sent to a museum for posterity.