The claims of science as to the age of man ride entirely on the dating methods used. This is, after all, science’s place, to use available tools and instruments to try to date artifacts and bones and stones by means other than conjecture and legend. But this number, in answer to the question “How long has Man been on the Earth?” has yet to be supplied. Answers have been given, but for the layman, even for science itself, these numbers have been so different as to mean really nothing at all. Because of the various dating methods used, various interpretations of the data accumulated, adjustments for mitigating or imagined mitigating factors, and downright ease of remembrance, the numbers are all over the place. Here is an example:
|Calister, Jeffrey C. Brief Review in Earth Science. Englewood Cliffs, NJ: Prentice Hall, 1993: 188-189, 242-243.||“Human-like mammals have existed on earth for a relatively short time — only about 0.04% of the earth’s existence.”||1,800,000 years
(0.04% of 4.5 billion)
|The World Book Multimedia Encyclopedia. New York: World Book, 1996.||“Most anthropologist believe that between about 400,000 & 300,000 years ago, Homo erectus evolved into a new species called Homo sapiens.”||400,000–300,000 yr|
|Boaz, Noel T. & Alan J. Almguist. Biological Anthropology: A Synthetic Approach to Human Evolution. Englewood Cliffs, NJ: Prentice Hall, 1997: 380.||“Asia fits into a framework of world wide appearance of Homo sapiens at about 500,000 years ago.”||500,000 yr|
|Leakey, Richard E., and Roger Lewin. People of the Lake: Mankind and its Beginning. New York: Anchor Doubleday, 1978: 252-253.||“The basic grade of Homo sapiens was probably around half a million years ago.”||500,000 yr|
|The World Book Multimedia Encyclopedia. New York: World Book, 1978.||“Most scientist believe that Homo erectus developed into the species Homo sapiens between about 400,000 and 300,000 yrs ago.”||400,000–300,000 yr|
|Lewin, Roger. New Scientist. 19 July 1997: 5.||“The results support the ‘Out of Africa’ model of human evolution. This holds that the modern human physique first appeared in Africa about 150,000 years ago, and then spread into the rest of the Old World, replacing existing populations of archaic human forms.”||150,000 yr|
This table is courtesy of Glen Elert at Hypertextbook.
Here are some more given dates for Man’s antiquity specifically. This is not just the hominid line, but actually direct human ancestors, or what is classified as Homo sapiens:
1. 195,000 years at EurekaAlert (2005),
2. 150,000 years at The Independent (2007)
3. 130,000 years at Washington State (2005?)
We show here that the science is not in agreement. Considering that some on the Creationist side argue that the entire Universe is no older than 7,000 years, a discrepancy of even 10,000 years is highly significant.
It is also worth the time to say a few things about science in general before proceeding. One of these things we should say is that science, by definition, must be falsifiable. While its determinations need not be proven wrong to be valid, science’s conclusions nevertheless need to, at least in theory, have the possibility of being refuted, or falsified. “Proof beyond any doubt” does not fall within the realm of true science; it falls under the category of dogma. Probability is what science provides, the higher the better. We need to recognize today, and guard against, the elevation of science to dogma. That is, if we are not too late already. Too many today, on all sides of this search, adhere to their positions as if they are literal and indisputable truth.
One could say, the way science accepts its newest dating methods as law, despite possible flaws any layman can see in the methods and assumptions used, that science has become, in some sense, a new religion. It wants to rely on belief in wildly speculative, if not fairy-tale, “theories” based on meager evidence and lots of conjecture. Indeed, from researching only dating methods alone, I have discovered to my chagrin some scientists who grudgingly stick to their method and theory even in the light of contradictory evidence, even after admitting and acknowledging their theories’ own weaknesses. For some, being shown problems with their system is not good enough. Until one comes up with something better, as they say, the authority will stand. As if something untrue is better than nothing.
In this, then, science, particularly regarding evolution and the ages of Man and the earth, is on little better footing than religion. In their explanations for the Origin of Man, and of the World, both religion and science contain elements of dogma, and their adherents are alike dogmatists.
But many thinkers, for later examples Feyerabend, Popper, Kuhn, have assured us how science works, about the “paradigms” or status quos, and how they shift over time. If you look at history, every new theory becomes at first met with rabid opposition. Scientists are reluctant to change for good reason. When the change involves a significant altering of the prevailing worldview, as was the case with the Copernican system, or with Darwin and Malthus’ expansions of Anaximander and Haeckel, among others, to form the basis for our current theory of Evolution, this rigidity in the face of change can turn, and has turned, to downright animosity and hatred. More than once have these debates brought the opponents to straight ad hominems, and at times, to blows.
This being so, let’s see about the methods used by science to determine the age of rocks, bones, and man.
We will start with radioactive dating, of which there are many types. The types we will discuss here are 1. Radiocarbon; 2. Rubidium-Strontium; 3. Potassium-Argon, and 4. Uranium-Lead. There are several others, including Argon-Argon, Samarium-Neodymium, Rhenium-Osmium, and so on. My hope is that an examination of the few examples of radioactive dating I have chosen, notwithstanding the particularities of the others, will be an adequate representation of them all.
We should not discard out of hand the admitted limitations of all radiocarbon dating methods. This is, first and foremost, that the proper use of radiocarbon dating is meant to be for rocks and minerals. Sedimentary rocks, and a few other types, cannot be dated accurately at all using this method. Nevertheless carbon-14 (C14) is used to date not only charcoal, but also recent organic materials like bone because of the high carbon content of living things.
Note on “Isotopes”
We know 300-340 natural isotopes occurring in our world, depending on which source you believe, a far greater number than actual elements. Some of these isotopes change and some do not, and all, it is claimed, are formed during chemical reactions, nuclear reactions, solar rays, and the like. The ones that change—the unstable sort—break down, eventually, into other isotopes.
A quick gander at what this very important isotope is should be beneficial. The word “isotope” comes from the Greek words isos and topos, meaning, when combined, something like “in the same place.” Isotopes are variants of certain elements that have the same number of protons (and electrons) but a differing number of neutrons. They maintain the same atomic number as their stable counterparts because the amount of protons, which determine the atomic weight, are the same. The ones we use to date with are unstable, they decay at what are claimed to be known rates. A stable isotope, species of which far outnumber the unstable sort, is not known to decay at all.
In 1913 Frederick Suddy and Margaret Todd coined the term, intending it to account for those elements of the Periodic Table which apparently occupied the same place and had the same weight. Suddy’s Nobel Prize for work done was concerned with radioactive, or unstable atoms. All elements are, we should say, composed of one or more isotope, and these isotopes are usually, as stated, stable. The efficient causes, of this instability in the unstable isotopes of concern to us here, according to theoretical science, is variously given as because a) they decay so slowly that they never really, for human purposes, ever completely decay (as with uranium isotopes), or because b) cosmic radiation is constantly keeping up the instability, and so creating new ones (like carbon-14 isotopes) or c) by decay itself, as in the case of slow rates of decay (as with radium). Since there are only 94 elements but over 300 isotopes, it should be mentioned, much of what occurs in nature is the product of isotopic activity, elements in a state of change.
1. Radiocarbon dating
With radiocarbon dating specifically some crucial assumptions, necessary for the method to work accurately, are worth noting. One is the assumption that the amount of carbon in the atmosphere has always been constant, and the other is that the rate of deterioration has been constant. Most adherents to radiocarbon dating admit that cosmic ray flux, disasters, volcanic eruptions, atomic blasts, and the like, can alter both the rate of decay and the amount of carbon in general. These mitigating factors are “handled” by using a “calibration factor,” itself set (paradoxically) by other means such as strata of discovery, tree rings, and known dates in history. In any case radiocarbon dating is only accurate up to 50,000 years, with its accuracy tailing off quite considerably once you reach 5,000 years into the past.
An interesting fact about radiocarbon dating is that the original half-life (the times it takes for an element to half-way reach stability) upon which the dating is based was figured at 5,568 years. Because of problems coordinating results with verifiable historical events , that number has been changed, and now it stands at 5,730 years.
A natural process, radioactive decay occurs when an atomic nucleus becomes unstable, for reasons mentioned, or whatever reason. When this occurs, the atom slowly (or not…) returns to a balanced state. The atom does this by releasing portions or parts until it achieves balance. Assuming a constant rate at which the radioactive element decays allows a ratio to be obtained whereby a specimen may be dated.
Radiocarbon dating is rarely used for dates older than 10,000 years anymore for anything much more than confirmation of other methods. Despite this, according to my research, it remains the most accurate of the methods for early dates.
2. Rubidium-Strontium dating
Another radiometric dating technique is Rubidium-Strontium dating. This is usually used by geologists to determine the age of rocks and rock formations.
This dating method, like many, is hyphenated because the decay of one element, in this case Rubidium 87, decays to a different one, here Strontium 87. Both elements are present in the minerals of many rocks, along with Potassium and Strontium 86, and Strontium is a sort of replacement for Potassium. Dates are determined by studying the minerals within several samples. A ratio is obtained as in other methods. In this case, the Strontium- 87-to-Strontium-86 ratio for each sample is plotted against its Rubinium- 87-to-Strontium-86 ratio on an isochron, a graph used to measure the results. If on this graph the results form a straight line, the samples are considered consistent, and the age adduced, probably reliable. The actual age of the sample is determined by the slope of the line on the graph.
For samples to be dated accurately, according to its adherents, they must be in their preserved ancient state, untainted by even fresh air. The minerals must have joined all at once to form the rock sample being used. The sample also must not have come into contact with water or any other fluid. The process is more drawn out than radiocarbon dating, and the +/- factor for machine accuracy and other procedural errors is high.
Two things I wish to mention. First, dating of fossils and rocks is a big business. One big reason for the recent plethora of varieties of dating methods has much to do with the big business it is. Second, something too many scientists by study and by trade do not know, is that when an age is given for any sample, such as “this rock is 4.6 billion years old +/- 30 million years,” this does not mean there is a range of possible dates. What it means is they allow that much room for error in the procedure.
3. Potassium-Argon dating
This method is often touted as the “only viable technique” for dating very old archaeological finds (U. of California Santa Barbara, Geochron Labs, e.g.). This method uses for its foundation the fact that Potassium 40 decays to the gas Argon 40. Similar to the other methods, the proportion of K-40 to Ar-40 determines the age, based on the understood, better to say accepted, rate of decay. It has been used to date materials to 50 billion years ago.
I should mention that Potassium is one of the most abundant elements on the earth. Here is an adherent’s opinion:
“The Potassium-Argon dating method is an invaluable tool for those archaeologists and paleoanthropologists studying the earliest evidence for human evolution. As with any dating technique, there are some significant limitations.
The technique works well for almost any igneous or volcanic rock, provided that the rock gives no evidence of having gone through a heating-recrystallization process after its initial formation. For this reason, only trained geologists should collect the samples in the field.
This technique is most useful to archaeologists and paleoanthropologists when lava flows or volcanic tuffs form strata that overlie strata bearing the evidence of human activity. Dates obtained with this method then indicate that the archaeological materials cannot be younger than the tuff or lava stratum.
Because the materials dated using this method are NOT the direct result of human activity, unlike radiocarbon dates for example, it is critical that the association between the igneous/volcanic beds being dated and the strata containing human evidence is very carefully established.
As the simulation of the processing of potassium-argon samples showed, the standard deviations for K-Ar dates are so large that resolution higher than about a million years is almost impossible to achieve. By comparison, radiocarbon dates seem almost as precise as a cesium clock! Potassium-argon dating is accurate from 4.3 billion years (the age of the Earth) to about 100,000 years before the present. At 100,000 years, only 0.0053% of the potassium-40 in a rock would have decayed to argon-40, pushing the limits of present detection devices. Eventually, potassium-argon dating may be able to provide dates as recent as 20,000 years before present.”
4. Uranium-Lead dating
This is another method often touted as the most reliable, especially for ancient ages and geological time. It is this method that has given us the age of the “oldest piece of earth.”
This is a zircon, and what it is, how it is composed, and what it does, is the meat and potatoes of this method’s success.
For radiometric dating Zircon has been indispensable. They naturally contain bits of uranium and can supposedly be dated using several procedures. They have been known to withstand change of structure over millenia.
“4.404 billion years was the age this method attributed to a valley in Australia. Some say that these zircons might be the oldest minerals on earth. In addition, the oxygen isotopic composition has been interpreted to indicate that more than 4.4 billion years ago there was already water on the surface of the Earth. This interpretation has been published in scientific journals but is the subject of debate.” Read some more here.
The main problem with this method is the same with the others. It relies on past consistencies, and also on a somewhat closed, even isolated system. Simple things can taint these experiments wildly, and it is not unknown to get samples millions of years apart in age drawn from the same spot. Here is one critique and another one for this and other methods here.
A good discussion for most of these methods, from a scientific point of view, can be found here.