Can we explain human technology merely by supernova explosions and blind chance? Some do. But in rare earth elements, we find hints of a better explanation. Science Magazine posted a look at the so-called “rare earth elements” of the periodic table. Consider some design implications of these elements. Introducing the rare earth elements (REEs), Thibault Cheisson and Eric J. Schelter call them “Mendeleev’s bane, modern marvels.”
The archaeological three-age system (Stone, Bronze, and Iron) organizes the history of humankind according to the central role of metals in technological evolution. From antiquity to the modern day, the exploitation of metals has required technologies for their mass extraction and purification, creating strategic importance for mineral deposits and metallurgical knowledge. Unlike other resources, metals are relatively amenable to recycling and to the creation of circular supply chains. This scenario is evident in historical developments for Fe, Cu, Al, Ti, Zn, Ni, and Sn with recycling rates representing between 15 and 70% of the current usage for those metals in the United States and the European Union. However, in recent decades, new technologies have emerged that rely on metals of previously limited use: lithium, cobalt, and the rare earth (RE) elements, among others. Rare earths are finding increasing use in communications — and display devices, renewable energy, medicine, and other practical applications that affect daily life. In this Review, we examine the past and present separation methods that have developed REs into an industrial sector, with a focus on recent advances. [Emphasis added.]
Rare Earths and Chemistry
As Evolution News touched on in January, Dmitri Mendeleev was the key player in describing a natural pattern among the elements that led to the modern periodic table. In his day, only six of the rare earth elements were known. His belief in an orderly universe led him to predict in 1869 that elements in the gaps would be found — as indeed they were — where he only had question marks. Cheisson and Schelter call these REEs “Mendeleev’s bane” because they frustrated his scheme.
To accommodate some of these troublesome elements, Mendeleev himself examined and confirmed their trivalent natures in oxides (RE2O3), materials that were initially assumed to be divalent. In the latter iteration of his Natural System of the Elements, Mendeleev tried to accommodate the known REs in analogy to the d-block metals, but this placement led to inconsistencies. Ultimately, Mendeleev never successfully set the REs in his periodic system, a frustration that may have contributed to his shift in research interest away from the periodic table after 1871. Without easily discernable periodic trends, and owing to the limited characterization techniques of the time, close to 100 erroneous new RE claims were made during the last part of the 19th century. By 1907, all REs had finally been isolated….
In spite of these challenges, Mendeleev stuck to his conviction that order would persist. 1907 was the year of Mendeleev’s death, so he had been partly vindicated by the time the REEs were found. Some of the REEs were fit into an “f-block” in the periodic table, consisting of two expanded rows called the lanthanide series (elements 58 to 71) and the actinide series (elements 90 to 103). This maintained the periodicity of the bottom two rows of the table by adding 14 elements between lanthanum-57 and hafnium-72, and 14 elements between actinium-89 and rutherfordium-104 (elements above 94 being artificially created in the atomic age). Specifically, “The REs are a family of 17 metallic elements formed by the group III (Sc, Y) and the lanthanide series (La–Lu).”
Considered to be metallic, they are called “rare earths” not because they are all geologically scarce, but because they are hard to isolate. “Chemically, REs demonstrate very similar properties with the prevalence of the +3 oxidation state under ambient conditions, a large electropositivity, and kinetic lability,” the article explains. These factors made them a bane to poor Mendeleev in the 19th century, but we know much more about them now, after years of perfecting techniques to isolate them. Their difficult identification provides a first take-home on rare earths: they were predicted, and eventually discovered, because of a man who believed in an orderly system of chemistry.
Rare Earths and Biology
Life uses comparatively few of the 103 natural elements. Most of them are abundant on the earth. The big four are carbon, hydrogen, oxygen, nitrogen. Next in line, according to David Nguyen at Sciencing, are seven other major elements, phosphorus, sulfur, sodium, chlorine, potassium, calcium, and magnesium, making up about 3.5 percent of our bodies. The last 0.5 percent consists of the 13 trace elements, iron, iodine, manganese, molybdenum, selenium, silicon, tin, vanadium, boron, chromium, cobalt, copper, and fluorine. Despite their minor appearance by volume, “living things would not be able to survive without trace elements,” Nguyen says. So far, that’s 24 of the 94 naturally occurring chemical elements to be essential for the human body.
Tin, by the way? Really? It is found in our tissues, but there is no evidence it has any essential biological function at this time, says the Agency for Toxic Substances and Disease Registry. Search the Internet for the body’s need for trace amounts of cobalt, chromium, silicon, and vanadium. It’s quite fascinating. Silicon, for instance, is used in our balance organs, and cobalt is used to absorb and process vitamin B12 and repair myelin around nerve cells.
In any event, one cannot always discount an element’s importance by its absence in the body. Not that long ago, scientists identified bromine as a vital element. It doesn’t abide in the body, but takes part in essential processes during the construction of collagen. “Without bromine, there are no animals,” concluded scientists at Vanderbilt University in 2014. They call it the 28th essential element.
Do We Need Them?
This brings us to REEs and biology. Do we need them? Do we rely on them? Cheisson and Schelter spend most of their article discussing the historical progress of isolating REEs. But then, they describe a new, young field of research looking into this question:
Rare earths are used extensively in medicine, especially as imaging agents. But until recently, they were believed to have no natural, biological importance. Surprisingly, Jetten, Op den Camp, Pol, and co-workers reported in 2014 an essential dependence of methanotrophic bacterium on LREs [“light” rare earths, belonging to the Cerium group]. They rationalized this requirement by the replacement of the generally encountered Ca2+ cation by a LRE3+ cation in the active site of the methanol dehydrogenase (MDH) enzyme (61, 62) (Fig. 3A). Following that discovery, RE-dependent bacteria have been found in many environments and have initiated a new field of research.
It’s too early to say if humans need rare earths, but now that bacteria — the supposedly most primitive life forms on earth — depend on some of them, the possibility exists that REEs will prove to be vital to all life on earth, perhaps in indirect ways. “Without doubt, these confounding elements will continue to provide surprises and opportunities for the progress of humankind,” the authors say.
Rare Earths and Applied Science
It’s only recently that rare earths have become vital to modern engineering. Now, they are eagerly sought elements for computers, cell phones, “communications — and display devices, renewable energy, medicine, and other practical applications that affect daily life.” Ions of yttrium and lutetium, for instance, have become useful for identifying and treating cancer. We rely on REEs when we use cell phones and computers and TV sets. While it is true that humans got along fine without REEs during the Stone Age, Bronze Age, and Iron Age, how much richer our lives have become recently because of the availability of these elements.
Rare Earths and Geology
Essential elements cannot just be part of a planet’s makeup. They have to be accessible at the surface. Astronomers say that all the elements heavier than iron-26 had to come from supernovae. What are the chances that sufficient quantities of heavier elements, including the cobalt, copper, zinc, bromine, and molybdenum in our bodies, and potentially the REEs that give humans technological opportunities, would have arrived at the sun or earth from a nearby supernova? What are the chances that they would percolate up to the crust from a molten planet during its formation? These sound look good questions for design scientists.
Rare Earths and Cosmology
The same questions apply to other stars and planets. Astrobiology is big these days: NASA tries to look for life beyond the earth. They look for habitable zones around other stars, and get excited when earth-size planets appear to orbit a star at a radius that allows the existence of liquid water. They try to identify biomarkers such as methane or oxygen in an exoplanet’s atmosphere. Many astrobiologists feel it is sufficient to “follow the water,” even speculating that life might exist in subsurface oceans of moons in the outer solar system, like Europa at Jupiter and Enceladus at Saturn. Water is remarkably well-suited for life, as Michael Denton has written in his book, The Wonder of Water. We know, however, that earth life needs far more than H and O. What about the other 26 essential elements? And what about those rare earths? Even though they are apparently not essential for life, did an intelligent creator supply those on the surface of our planet with the foreknowledge that designed beings would someday make good use of them?
Rare Earths and Rare Earth
In 2000, Ward and Brownlee published a controversial book, Rare Earth: Why Complex Life Is Uncommon in the Universe. At a time when most scientists assumed there must be millions of complex civilizations in the Milky Way alone, the authors rained on their parade, arguing that the requirements for complex life are so stringent, living worlds like ours could be rare exceptions — perhaps unique.
This brief look into rare earth elements may provide additional support for their rare earth hypothesis. The more stringent the requirements, the better the evidence for design. REEs offer a new generation of chemists, biologists, geologists, physicists, engineers, astronomers, cosmologists, and philosophers opportunities to investigate profound questions about these elements. Why are they here? Where did they come from? Is the naturalistic answer plausible? Do they serve a purpose? The answers could inspire additional chapters to The Privileged Planet.