With steadily mounting evidence that points to a cosmic origin of terrestrial life, a cultural barrier prevails against admitting that such a connection exists. Astronomy continues to reveal the presence of organic molecules and organic dust on a huge cosmic scale, amounting to a third of interstellar carbon tied up in this form. Just as the overwhelming bulk of organics on Earth stored over geological timescales are derived from the degradation of living cells, so it seems likely that interstellar organics in large measure also derive from biology. As we enter a new decade - the year 2010 - a clear pronouncement of our likely alien ancestry and of the existence of extraterrestrial life on a cosmic scale would seem to be overdue. Received 20 November 2009, accepted 10 December 2009, first published online 29 January 2010

/pdf/the-astrobiological-case-for-our-cosmic-ancestry-264p3f28c2.pdf

The astrobiological case for our cosmic ancestry

Fossils of Cyanobacteria in CI1 Carbonaceous Meteorites: Implications to Life on Comets, Europa, and Enceladus

In this Chapter I introduce aspects of the physics and chemistry of water that are relevant to the basic understanding of hydrothermal solutions, hydrothermal processes and systems. Given the context of this book, this introduction is perhaps somewhat elementary and by no means exhaustive, but for the reader who wants to further his/her knowledge I provide a list of a range of useful and/or essential published works. Water is an oxide of hydrogen, composed of two H and one O atoms forming a polar molecule, meaning that the H atoms posses a weak positive charge and the O atom a weak negative charge and. This polarity is extremely important because it makes water a good ligand for cations, enabling processes of hydration and hydrolysis

Water and Hydrothermal Fluids on Earth

Seasonally frozen soils and permafrost are widespread on Earth, accounting for more than 50% of the Earth’s land surface (Toll et al. 1999). Frozen soils have strong implications on freshwater hydrology, terrestrial ecology and the climatic system. For example, frozen soils are largely impervious to water, and during the release of water during spring, thaw may significantly increase runoff, contributing to severe flooding. In the last two decades, tundra soils and permafrost attracted serious attention from the entire global change community when it became clear that global warming is much more pronounced in the polar area than elsewhere. The climate projections suggest a continuation of the warming trend, with an increase in mean annual temperatures of 4–5°C by 2080 (Elberling and Brandt 2003; Callaghan et al. 2004). The thawing of permafrost, combined with melting of sea ice, is predicted to cause disastrous events including flooding, karst and erosion, accompanied by accelerated degradation of terrestrial carbon. Microbiology of permafrost and frozen soils is at its infancy. Until recently, permafrost has been addressed by microbiologists primarily as a natural depository of ancient forms of life. However, the recent finding of measurable winter gas emission to the atmosphere (see below) demonstrated that subzero microbial activity is an important driver of the observed global changes. This activity may significantly accelerate permafrost degradation under global warming; and this acceleration should be detected well before the visible signs of permafrost thawing appear. This review focuses on microbial activity in permafrost and frozen soils. The starting point will be methodology; how to measure subzero metabolic activity, and how to distinguish reliable data from experimental artifacts. This is followed by a survey of available data on spatial variation and magnitude of microbial activity in frozen soils, mainly in the North Slope of Alaska. Finally questions crucial for mechanistic understanding of subzero activity will be (tentatively) answered:

Microbial Activity in Frozen Soils

It is puzzling why life on Earth consisted of prokaryotes for up to 2.5 ± 0.5 billion years (Gy) before the appearance of the first eukaryotes. This period, from LUCA (Last Universal Common Ancestor) to LECA (Last Eucaryotic Common Ancestor), we have named the Lucacene, to suggest all prokaryotic descendants of LUCA before the appearance of LECA. Here we present a simple model based on horizontal gene transfer (HGT). It is the process of HGT from Bacteria to Archaea and its reverse that we wish to simulate and estimate its duration until eukaryogenesis. Rough quantitation of its parameters shows that the model may explain the long duration of the Lucacene.

LUCA to LECA, the Lucacene: A model for the gigayear delay from the first prokaryote to eukaryogenesis

The idea that comets may be connected with the origin of life on Earth was considered heresy a few decades ago, with scientists shying away from this possibility as if from a medieval superstition. However the case that comets may have contributed at least the complex organic building blocks of life has become very strong, and mechanisms have now been identified whereby comets may incubate and transfer microbial life from one cosmic habitat to another in the Galaxy. The latter process cometary panspermia was pioneered by the late Sir Fred Hoyle and one of the present authors in the early 1980's. A theory that was once controversial is slowly gaining scientific respectability and support.The recent surge of interest in astrobiology has led to a spate of books in astrobiology - combining astronomy and biology - but in most of these, cometary panspermia is dealt with only cursorily. The present book sets out the case for cometary panspermia in a cogent way, combining evidence from space science, celestial mechanics, geology and microbiology. It should be an essential part of any university course on astrobiology, and also serve as a reference textbook for researchers in the field.

Comets and the Origin of Life

Expanding Horizons of Life

Handle everyday research tasks with reliable, citation-backed results

Your personal Research Agent to handle research tasks with citation-backed results

Popular Tasks used by Researchers

How can I help with your research?

Meet SciSpace

Get more enhanced response by uploading the PDFs you want me to reference.

No relevant PDFs in your library

SciSpace is the AI research assistant for academics. Run systematic literature reviews on 280M+ papers, and write papers with cited sources. Trusted by 1M+ students, PhDs & researchers.

SciSpace | AI for Research

Analyze PDFs

Code & Manuscripts

Funding & Grants

Literature & Patents

Medical & Clinical Data

Systematic Review

Visualize & Present

Web & Data

Build a Google Scholar-like website for your research.

Build a website

Create charts and images for your research

Create a Chart

Write a paper for submission to a journal

Draft a manuscript

Patent Search

Design eye-catching scientific posters in minutes.

Scientific Poster Generation

Systematic Literature Review

One task is running at the moment. Your messages will be shown right after.

Drag and drop or click here to browse

Loved by <highlight>1 million+</highlight> researchers

Extract a list of specific topics and their sources from unstructured text

Topics

Compare and analyze relevant papers that matches with your search

Papers

Get insights from PDFs and bookmarked papers from your library

My library

Recent searches

Try searching for:

Catch AI-generated content in scholarly and non-scholarly content

{ai} Detector

Ai Writer

Get PDF Summaries, highlighted text explanations 

Chat with PDF

Effortlessly create in-text citations and bibliographies in APA and 2,500 other formats

Citation generator

Get explanations, summaries, and answers on academic papers

Ease up your research workflow with {scispace}'s cohort of exciting AI tools

Elevate your academic writing skills and convey your ideas the way you want

Paraphraser

Explore our range of reading and writing tools

Your file is being prepared and should be ready in a few minutes. If it's a large file, it might take a bit longer. You can close this window, and we'll email you the file when it's done.

You have reached a maximum limit of <strong>{limit}</strong> columns in the table. Remove at least <strong>1</strong> column to add or create another one.

Chandra Wickramasinghe

Author Tools

Chat about Author

Papers

Comets and the Origin of Life

Expanding Horizons of Life