2009 Annual Science Report

Massachusetts Institute of Technology Reporting  |  JUL 2008 – AUG 2009

Executive Summary

Molecular and Fossil Records of Complex Life

During the reporting period, members of the MIT Team of the NAI have been investigating aspects of the molecular records of animal evolution. We do this through complementary studies of the genomes of modern taxa and the ancient organic molecules preserved in sedimentary rocks. In the Jacobs laboratory, studies of the jellyfish Aurelia are yielding greater understanding of the evolution of sensory and neural systems in the various life history stages of Cnidaria, the most basal branch of animals having well-established multimodal sensory systems and neural organization. Studies of Neanthes, a Polychaete worm, are yielding insights into the basal evolution of sensory organization in the Bilateria. These observations are shaping a better understanding of shared aspects of gene regulation of sensory organization in Cnidaria and Bilateria, and the discretely different modes of sensory organization and neural complexity found ... Continue reading.

Field Sites
19 Institutions
11 Project Reports
28 Publications
6 Field Sites

Project Reports

  • Timscales of Events in the Evolution and Maintenance of Complex Life

    This project involves high precision dating of major events in earth history. Using the decay of uranium (U) to lead (Pb) in the mineral zircon we are able to date 600 million year old rocks to ± less than 1 millon years. Such precision allows us to investigate rates of change in the ancient past from climate to evolution.

  • Astrobiological Exploration of Mars

    NASA spacecraft have discovered both chemical and physical evidence that liquid water once flowed on the martian surface. Close examination of the images and spectroscopic data from these spacecraft, and understanding what they tell us, are critical to selecting the best sites for future rover missions. This project aims to maximise the knowledge gained from orbiting and landed spacecraft and apply it effectively in future planning and execution of new missions.

    The key questions for astrobiology are not so much “was water present?” as “what were its properties?” and “How long did it persist?” Using thermodynamic calculations, one can approach both questions, using mineral identifications made by the MER rovers and CRISM. We find that waters at Gusev and Meridiani planum grew extremely salty as evaporation proceeded, reaching conditions that would challenge known life on Earth. We also learn that in a number of places on the martian surface, minerals deposited billions of years ago as a result of water-rock interactions have seen little or no water since that time.

  • Paleoecology of the Mistaken Point Biota

    The origins of animals has remained shrouded in mystery since the origins of paleontology, principally because of their abrupt appearance in rocks dates at around 530 Ma with little or no sign of possible antecedents in Precambrian rocks. This does not mean though that older rocks are devoid of life – indeed rocks of the last half of the Ediacaran period (~580-542 Ma) are chock full of interesting but enigmatic and unmistakably non-animal forms. Maybe the most interesting of these are the rangeomorphs, fractally-organized organic forms seemingly designed to feed on dissolved nutrients in the sea water via passive absorption across their bodies. Curiously modern sponges are also designed to feed on nutrients extracted directly from sea water, but they do so in a fundamentally different manner. Why would these rocks have one type of organization but not the other when both work equally well, all things being equal? Our recent exploration of these rock in the Mistaken Point sections of Newfoundland have revealed that one already described taxon, Thectardis, might indeed be a sponge, and as such the oldest known macroscopic animal form.

  • Origins of Multicellularity

    One of the earliest events in the evolution of animals was the origin of multicellularity. By studying the closest living relatives of animals, the choanoflagellates, we can begin to reconstruct the biology of the unicellular ancestors from which all living animals evolved.

  • Modelling Planetary Albedo

    What kind of environments could provide opportunities for life in general and for the advent of complex life specifically to emerge? If there were complex life present, what features would it produce? Could we remotely characterize such habitats and the features of complex life on extrasolar planets light-years away with current and future NASA missions?
    These are the three main questions we work on in this part of the project.

    ROADMAP OBJECTIVES: 1.1 1.2 4.1 4.2 6.2 7.2
  • Environmental Oxygen and the Rise of Metazoans

    We seek to understand when and how levels of oxygen rose in the environment,
    and how this rise may have impacted the evolution of complex life.

  • Evolution and Development of Sensory and Nervous Systems in the Basal Branches of the Animal Tree

    Sensory and Nervous systems are intimately related to the complexity, motility and environmental responsiveness that characterize animal life. We examine the early evolution of animal sensory and nervous systems through investigation of neural markers, as well as developmental gene expression and function in basal branching animals, including jellyfish, polychaete worms, and sponges.

  • Genomic Relationships Among Basal Metazoans

    The origin of animals, and animal complexity, requires an accurate and precise understanding of both the phylogenetic interrelationship among the earliest evolved animals and the paleoecological milieu within which they evolved. Our work has shown that sponges are indeed the first animals that evolved that still have living descendants, and that sponges are not a natural group. Instead, some sponges are more closely related to more complex animals like humans and jellyfish than they are to other sponges (e.g., bath sponges). This suggests that the origins of animal complexity is rooted in sponge paleobiology, and that the earliest animals were designed to eat bacteria and organic carbon instead of other large eukaryotes like other sponges or plants.

  • Geochemical Signatures of Multicellular Life

    Organic molecules preserved in rocks provide a geological record of past organisms and processes. These complement the record left by visible organisms and can often provide information on the, otherwise invisible, microbial world. This part of the project is designed to improve our knowledge of 'molecular biosignatures’ now and in times past. This part of the project also offers a window into the presence of complex life prior to the point at which animals became large enough, or hard enough, to leave a visible record.

  • Metabolic Networks From Single Cells to Ecosystems

    Metabolic networks perform some of the most fundamental functions in living cells, including energy transduction and building block biosynthesis. While these are the best characterized networks in living systems, understanding their evolutionary history and complex wiring is still a major open question in biology. Here we use mathematical models and computer simulations to understand how metabolic networks gradually evolved the degree of organization necessary to sustain complex multicellular life. In particular, we ask (i) how metabolism changed as the level of oxygen gradually rose in the atmosphere, (ii) what metabolic structures are associated with cell-cell communication, and (iii) whether general optimality principles can help understand the architecture of biochemical networks.

    ROADMAP OBJECTIVES: 4.1 4.2 5.2 6.1
  • Paleontological Investigations of the Advent and Maintenance of Multicellular Life

    We have focused research on functional physiological investigations of early land plants, products of an origin of complex multicellularity distinct from the events that gave rise to animals. We have been able to show show basic attributes of anatomy were modified to facilitate physiological adaptation of early land plants. We also completed a functional analysis of early multicelullar organisms that stresses the constaints imposed by diffusion and the means of circumventing them.