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Abstract
This article presents a study of evolutionary emergence based on a simple description of system change. It suggests a relation that, though unexpected, is in agreement with established data, and reveals that the underlying measure of evolutionary change is information. This leads to a number of surprising implications, and to some sobering thoughts about the future.
In evolutionary theory, "emergence" signifies the spontaneous appearance of a new physical configuration or form of behavior in a highly complex system such as a biological life form or a social structure. Unfortunately, unless rooted in a more detailed theory, emergence can neither elucidate the mechanism of sudden change, nor provide any overall coherence to evolutionary history. Such clarification would be useful, both for establishing the underlying principles of evolution and for comparing features of behavior.
Consider the "logistic" model of growth common to many processes: an initial exponential
increase of a parameter, x (such as length or population number),
is followed by its saturation at a limiting value, X. Describing this behavior mathematically generates
the sigmoid, or S-shaped, growth curve, which is widely applied in such disparate fields as
paleontology, medicine, and social theory, among others. The great historian of science Derek de Sola Price
observed that as saturation is reached, a process may occur that he called "escalation." If there is a slight
change in the nature of x, a new logistic curve may rise above the old, to a new saturation level; a
third sigmoid curve may then rise above the second, and so on - a succession of S-curves (figure 1).
This process may be expected of the multidimensional parameters of complex systems. Such behavior is
equivalent to sequential emergence, but it can be described by an extension of the equation for simple
logistic growth.
In most systems of interest, the growth curve cannot be displayed because the evolving variable (or set of variables) is unknown. It is easy, however, to discern the system transitions - when new modes of behavior or taxonomic groups come into being - and the points in time at which they occur. The mathematical description of the growth curve can then be used to find a relation between the times of the successive transitions. If we calculate the time from the end of the series of escalations back to the beginning of the kth escalation cycle, it can be predicted that the logarithm of this tkpast decreases linearly as k increases. Plotting logtkpast versus k should result in a straight-line graph, known as the "trajectory" of the process.
To test this prediction in the study of evolution on Earth, we have to specify the
major emergent events that initiate the successive cycles. Because the range of phenomena
to be covered is vast, and to avoid subjectivity of choice, we divide our consideration of Earth's
history into three parts: (1) the period before organic evolution began, (2) the period of organic
evolution, and (3) events attributable to the actions of mankind. In each of these periods there is
a general consensus, established and acknowledged by scholars using their own independent criteria,
about the pertinent categories and judgements that define critical events. Accepting those consensus
judgments, without going into the appropriateness of each point, we can identify the following as critical
transitions in evolution on Earth. In table 1, dates are given in years before the present (BP) except for events 11
and 12 (marked with asterisks), where they are given with respect to the calendar year 2140.
| Number | Event | Date (years BP) |
| 0 | Big Bang | 1-2 x 1010 |
| 1 | Solidification of Earth Prokaryotic life |
3.6 x 109 3.4 x 109 |
| 2 | Eukaryotic radiation | 6-9 x 108 |
| Appearance of: | ||
| 3 | class Mammalia | 1.5-2 x 108 |
| 4 | superfamily Hominoidea | 2.5-4 x 107 |
| 5 | family Hominidae | 4-10 x 106 |
| 6 | genus Homo | 1.5-2 x 106 |
| 7 | archaic Homo sapiens | 2-5 x 105 |
| 8 | H. sapiens sapiens | 7-10 x 104 |
| Development of: | ||
| 9 | communal villages | 1-2 x 104 |
| 10 | writing | 3-5 x 103 |
| 11 | printing | 6.95 x 102 * |
| 12 | digital electronics and computing | 1.95 x 102 * |
* These dates are taken with respect to the calendar year 2140.
The evolutionary trajectory of these points (figure 2) shows a convincing fit of the points to the line,
covering thirteen events and more than eight orders of magnitude of time. However, two
points should be noted. First, to obtain this agreement, it was necessary to omit from the list
two taxa, the order Primates and suborder Anthropoidea, that are commonly included in the textbook
phylogeny of H. sapiens sapiens, and also to leap directly from Metazoa to Mammalia,
passing over vast amounts of organic evolution. This can be explained by the fact that, as
we will shortly see, x, the parameter of this trajectory, represents information
in various forms. This is not a purely biological variable, so some departure from biological
criteria is not surprising.
Second, the change of reference of the last two points reflects a question we have not yet discussed: in describing times as years "before the present," exactly what, in this geological context, do we mean by the present? This is significant for events 11 and 12, because they are recent and well defined. To make these points agree with the earlier trajectory, it is necessary to add 140 years to their actual times. This means that our reference for the "present" should be approximately the year 2140 C.E. As we will see, this an important change.
In examining the list of events, we cannot help but conclude that the parameter describing
evolution on Earth is the enhancement of information generation, storage, processing, transfer,
representation, and control.
We, H. sapiens sapiens, being the originators of the last five events, ranging from the initiation of
facile speech communication to digital data transfer, easily recognize their fundamentally informational
nature. Coherence of the logistic escalation process demands that this parameter extend throughout the
evolutionary trajectory, albeit perhaps in different forms. Indeed, information transfer was clearly a
key aspect of the first organic or preorganic molecular reproduction.
Also, we cannot contemplate the evolutionary trajectory without being alerted to its relation with entropy, that universal directional arrow of change. It is well known that the difference between the entropy of a system and the information it contains is merely one of measurement units; in fact, mathematically the two parameters are complements; a decrease of one is an increase of the other. Through this correspondence we see the continuity of organic evolution with earlier cosmological events. It is also known that, in addition to an overall increase of entropy, the second law of thermodynamics allows, and even predicts, a growth of local ordering phenomena - that is, a local increase in information. This, too, is captured by the trajectory.
Two points of interpretation must be emphasized. First, the events we have listed were not the only
significant transitions in the time-frame described; other important biological and cultural
innovations and informational advances occurred. These are omitted, however, because the trajectory
displays only those events that mark major redirections of the process, within which the other changes
can manifest themselves.
In addition, we must avoid the conclusion that information enhancement and change is an underlying driving mechanism of evolution. As with entropy, changes of information that occur during evolution are the result, never the cause, of physical and chemical processes. Information is therefore only the measure of the progressive change.
Finally, the linear form of the trajectory begs for extrapolation into the future. From the line
it can be seen that point 13, the next critical evolutionary event, can be expected in 35 B.P. - about
the year 2105 C.E. Since this is only a little over a century in the future, it is likely to follow
from some development whose first seeds are already visible. The trajectory also indicates that the
event will be informational in nature and will have, at the least, a major technological component.
These conditions suggest three possibilities:
Each of these already exists in rudimentary form; event 13 would mark a breakthrough that initiates a period of intense development and change.
Another concern is the close spacing of subsequent transitions: event 14 only 30 years later; event 15 just ten years after that; and future events even closer together. Having witnessed the social turnover brought about by digital computation and communication, event 12, we must realize that a series of comparable radical changes will likely be more than society can easily absorb. This is an indication that the evolution we have experienced for 10 billion years is reaching a state beyond which it cannot proceed without a fundamental and radical change of direction, form, mechanism, and nature.
That future is opaque, but because of the relation of information to entropy we can draw an analogy
between this imminent (approximately 140 years distant) change and the entropic behavior observed in matter during a
thermodynamic phase change, such as the condensation of steam to liquid water or the freezing of water
into ice. This sort of reasoning is a dubious undertaking but, if carried through quantitatively,
it indicates that a hidden evolutionary variable, forecast by the change at event 13, may come into
prominence, altering the future evolution of Earth and its residents and products. This, and other issues
raised by the trajectory are discussed in The Evolutionary Trajectory: The Growth of Information in the History and Future of Earth (Gordon & Breach, 1999).
Richard L. Coren is a professor of electrical and computer engineering at Drexel University in Philadelphia, Pennsylvania.
Caleb Brown is an illustrator and biologist living in Montana. By day he drives a delivery van, and by night he draws pictures with his computer.
Museum of Paleontology - provides online exhibits on phylogeny, geology, evolution, and more. From the University of California at Berkeley.
P>Biology Links: Evolution - an extensive set of links related to evolution. From Harvard University's Department of Molecular and Cellular Biology.Talk.Origins Archive - a collection of articles and essays devoted to the discussion and debate of our biological and physical origins.
Waking Up in the Universe - a review of the Royal Institution Faraday Lectures given by Richard Dawkins in 1991. Includes audio and video excerpts. An HMS Beagle Featured Essay.
