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Current Scientific Knowledge on Cosmic Evolution and Biological Evolution
The Pontifical Academy of Sciences devoted its Plenary Session of 31 October–4 November 2008 to the subject: ‘Scientific Insights into the Evolution of the Universe and of Life’. The Plenum was attended by 45 members of the Academy and by 14 invited guests. Lectures were given by 23 members and 8 additional lectures were given by invited experts. Ample time was devoted to discussions.
The chosen subject is very topical for the sciences as well as for philosophy and theology and it is also of relevance for the general public. A majority of the lectures and debates concentrated on presenting contemporary scientific insights into the evolutionary processes and on integrating these insights into our common world-view. The Academy also provided a platform for a discussion on the relationship between acquired scientific knowledge and other branches of knowledge, including a philosophical approach and traditional wisdom such as that to be found in Biblical writings. On the first day of the session, the Academy specifically addressed established knowledge, theories, models and open questions relating to cosmic evolution. Ever more powerful instruments (telescopes, etc.) allow us to explore developments that occurred in the far past despite the limitation imposed by the speed of light. Another frontier of scientific investigation is penetrating ever smaller dimensions, revealing the laws of the cosmic microworld. Recent investigations both in the very big and in the very small confirm and strengthen the previously reached scientific consensus that the cosmic evolution of galaxies and of matter is an undeniable fact. The cosmos and time may indeed have a temporal origin, contrary to ancient Greek opinion (with the exception of Plato – Timaeus) which generally regarded them as eternally cyclical, without a beginning and an end. The exact time of that origin is subject to a small but fundamental uncertainty.
Several lectures raised questions about the existence of life in other parts of the universe. Theories and logical speculations attempt to provide answers to these pertinent questions. However, until appropriate observations and investigations in our galaxy (it may be observed that over 300 extra-solar planets have already been discovered), and perhaps in the future in other galaxies, are possible, science cannot provide solid answers to these questions. The origin of life on earth was also discussed, with an exposition of recent progress in the field, in the light of what man is learning about our galaxy as well.
We can now understand biological evolution at the molecular level. Hypotheses that had been presented earlier have been validated with novel research strategies. Genetic variation, the driving force of biological evolution, is shown to involve a number of different molecular mechanisms. Genetics as well as computational comparison of DNA sequences allow us to explore these mechanisms, which can be classified into three natural strategies (local DNA sequence changes, intragenomic rearrangement of DNA segments, and acquisition of foreign DNA segments) of different evolutionary qualities. Interestingly, both specific products of so-called evolution genes and a number of non-genetic elements contribute to overall spontaneous mutagenesis, and very low rates of mutagenesis underlie the genetic stability of living organisms.
Natural selection results from the way by which living organisms deal with encountered living conditions to which both the physicochemical environment and the presence of other organisms in a given ecosystem contribute. Most of the prevalent substrates for natural selection are phenotypes resulting from the presence and activities of expressed gene products. However, particularly for eukaryotic organisms, genome organisation and the compacting of chromosomes into chromatin can also contribute to the outcome of natural selection. The presence of evolution genes determining the evolutionary fitness of living organisms is selected at the population level by second-order selection. Positive selective pressure is also exerted by long- term symbiotic associations between different kinds of microorganisms – for example between humans and several kinds of microorganisms. Organelles, such as mitochondria and chloroplasts, testify to the evolutionary importance of symbiotic cohabitation.
The Plenum devoted ample time to primate and in particular to human evolution. In this evolutionary pathway a remarkable increase of the size of the brain has occurred. Many novel genes that have been added during the course of evolution are expressed in the brain. In addition, importance can be attributed to the development and establishment of a complex neuronal network during childhood. All of these evolutionary and developmental changes are generally seen as a basis for the capacities for consciousness, intelligence and freedom, and their possible development. These attributes allowed human beings to develop what is generally known as ‘culture’. Since cultural evolution facilitates the organisation of human lives, the pressure of natural selection on a number of distinct traits in the human population is diminished, although, of course, it still acts on many other features. In view of this situation, the Academy calls for humanity to exercise responsibility when intervening in the natural evolutionary processes and to use scientific knowledge and its technological applications to safeguard the conditions for survival of all species and, in particular, to assure the dignity and the wellbeing of humans.
We have to be aware that the impact of human activities on our environment is not unique but is now as great as any factor affecting living things during the whole period of the existence of life on earth. Many other living beings, including bacteria, which are not provided with consciousness, may also contribute to changing in a considerable way the environment and thus also the pressure of natural selection. The Plenum noticed a remarkable example of this situation: it is generally thought that early life on earth was largely anaerobic as long as the atmosphere contained no or very little oxygen. This changed after photosynthesis was developed through the biological evolution of microorganisms and, in particular, when plants acquired the capacity for photosynthesis. It is only thanks to this evolutionary progress that aerobic life became possible, including that of higher animals and human beings.
This striking example of interdependencies between biological and geo logical evolution on the planet should not be seen as a justification for human society to abuse precious natural resources and to cause climate change by its modern lifestyle; indeed, quite the contrary. Since we are the only being with consciousness that is in the position of affecting the condition of life on earth as a whole, we have a special responsibility, clearly outlined in Holy Scripture, to care for the earth.
It is largely due to considerable improvements in human living conditions – among which we may also list the strong improvement in therapeutic and preventive medical care – that in the last hundred years both human life expectancy and the global density of the human population have strongly increased. Justice at a global level that provides sufficient food and water to all, without injuring the environment, is an increasing imperative.
On several occasions the role of chance was addressed by the Plenum, in relation to both cosmic and biological evolution. According to present scientific knowledge, chance is required in natural reality in order for it to be pre pared for rapid adaptation to newly developing situations. In biological evolution, partial randomness in the generation of genetic variants may render populations of organisms more adaptable to changing living conditions.
From the natural scientist’s point of view, natural evolutionary processes largely reflect self-organisation, which depends on the intrinsic properties of matter and energy. This holds for cosmic and for biological evolution, which must cover about 15,000 and almost 4,000 million years respectively.
It is important for scientific knowledge on evolution to become integrated into our world -view and for our world - view to be steadily updated. The extraordinary progress in our understanding of evolution and the place of man in nature should be shared with everyone. This will help to guide humans and the next generations in decisions that contribute to cultural evolution, including agricultural practices, societal developments, medically-relevant activities and environmental emissions, based on reason, fairness and justice. A wise use of available scientific knowledge not exclusively for the benefit of the human population but also for the safeguarding of a rich bio-diversity and of natural resources can contribute significantly to a harmonious evolution of life on our planet and the wellbeing of future generations. Furthermore, scientists have a clear responsibility to contribute to the quality of education, especially as regards the subject of evolution, and to the quality of knowledge that education conveys.
The plenary session confirmed the Pontifical Academy of Sciences in its awareness of a remarkable strengthening in recent years of our scientific knowledge about cosmic and biological evolution. One could see in these evolutionary processes a confirmation of the theological concept of creatio continua (creatio and conservatio) which states that creation is a permanent process of participation of being by the Being by essence, who deserves our respect and our praise. Evolution and creation fill us with wonder and awe and remind us of the Biblical benediction: ‘And God saw every thing that He had made, and, behold, it was very good’ (Gen 1:31).
Revised draft of 24 January 2009 by Prof. W. Arber (2), with suggestions made the academicians N. Cabibbo, P. Léna (2), Y. Manin, J. mittelstrass, W. Phillips, P. Raven (2), I. Rodríguez-Iturbe, M. Singer, W. Singer
Pontificia Academia Scientiarum, Scientific Insights into the Evolution of the Universe and of the Life, The Proceedings of the Plenary Session 31 October - 4 November 2008 (Vatican City: Pontificia Academia Scientiarum, 2009)