Origin and Evolution of Life on Earth

Section I: Abiogenesis and Geology

January 14 Introduction to the course

We begin with a first look at the theory of A.I. Oparin, the Russian biochemist who began the scientific study of abiogenesis during the first half of the 20th century. His basic hypothesis forms the theme of the course, although many of the specifics of his proposals are no longer widely accepted.

January 16 Abiogenesis

The study of abiogenesis [life from non-preĎxisting life] begins by looking at the first two steps in the process: the abiogenic synthesis of monomers and, polymerization. Reading: EE chapter 5 (Lazcano).


January 21 Evolution of the first living system

Oparin's theory provides a framework for discussing self-assembly of the first cells and the interface between non-living and living systems. Once living systems exist, they evolve through the Darwinian mechanism of Natural Selection.

January 23 The rock cycle

The origins of life is very tightly linked with the active chemistry of Earth's surface. In this lecture we take a quick look at the dynamics of Earth as a system. Reading: EE chapter 10 (Siever).


January 28 Introduction to Historical Geology

The historical development of the geological timescale and the principles of stratigraphy are introduced. We review radiometric dating methods and other aspects of dating ancient rocks, on the Earth and elsewhere.

January 30 Earth origins

The planetesimal or accretion theory for Earth's origin is important for constraining the range of possible components available for abiogenesis. Much of what we know of the conditions on early Earth comes from the study of meteorites and the study of nearby planets [comparative planetology]. Reading: EE chapter 2 (McElroy).


Section II:  Abiogenesis and Evolution

February 4 • QUIZ 1

February 4 Chemical Evolution I

The abiological synthesis of organic precursors to biomolecules could have occurred on the early Earth. Or were they generated in space and transported here in comets and meteorites? We examine the evidence for Earth's earliest environments and the abiological synthesis of simple organic compounds.

February 6 Chemical Evolution II

The synthesis of monomers. What kinds of chemical reactions could have produced simple organic compounds? Are these chemical reactions compatible with what we know about initial conditions on the planet? We review the research in this field, starting with a very famous experiment by Stanley Miller and Harold Urey in 1953.


February 11 Polymerization:  the generation of macromolecules

The organic molecules that are used to build living systems are mostly polymers, larger molecules made up of smaller subunits. Nucleic acids, lipids, complex carbohydrates and proteins all fit into this category. The mechanisms and environments that supported the genesis of such molecules is an active area of origins research today. Reading:  EE chapter 3 (Matthews).

February 13 RNA and DNA: The origins of the genetic system

Nucleic acids play a special role in living systems because they contain the genetic information that is encoded and passed on from organism to organism. How did the genetic code get started and how has it evolved?


February 18 Cellular metabolism and photosynthesis

Living organisms depend upon the packaging of life into membrane-bound units called cells. Cells use energy in ways that are common throughout life. How do cells manipulate and control the chemical energy that is contained in certain molecules? We explore the origins of photosynthesis and related mechanisms for creating food from inorganic sources. Reading:  EE chapter 8 (Margulis).

February 20 Self-Assembly: The bugaboo of abiogenesis

This is where Oparin's theory is weakest - we are long way from understanding how a collection of molecules can assemble into a living system. We explore some of the different directions this topic holds at the present time, from materials science and physics to experimental attempts to build actual cells. Reading:  EE chapter 4 (Deamer).


February 25 • QUIZ 2

February 25 Darwinian Evolution 

Once a primitive living system was up and running on Earth, the Darwinian process of Natural Selection provides a well-studied basis for subsequent evolution and development of life.

February 27 Evolutionary Systematics

Introduction to the science and methods of Systematics, the study of diversity of life on Earth; including classification, taxonomy and species concepts.


March 11 Phylogeny

Building The Tree of Life (tol). Traditional methods in the construction of phylogeny. Molecular systematics and molecular clocks.

March 13 On the origin of the Eukaryotic cell

We take a digression into a discussion of the origin of the eukaryotic cell, which probably occurred during Proterozoic time. This leads into a discussion of a fundamental debate in evolutionary biology about the significance of lateral gene transfer, symbiogenesis, and reticulate evolution in determining the fundamental units of biological classification -- Domains and Kingdoms. Reading:  EE chapter 8 (Margulis).

Section III:  Precambrian Life

March 18 The Archean fossil record.

We survey the fossil record for earliest life on Earth. This includes direct evidence of prokaryotes, indirect chemical evidence and trace fossils. Reading:EE chapter 6 (Strother & Barghoorn).

March 20 The Proterozoic fossil record

The record of life during the Proterozoic is based on unequivocal microfossils preserved in cherts and in siliciclastic sedimentary rocks. We survey the kinds of fossils, including chemical fossils and biomarkers, that characterize the later half of Precambrian time. Reading: EE chapter 9 (McMenamin)



March 25 • QUIZ 3

March 25 Stromatolites: A modern analog of Precambrian Earth

Stromatolites are organo-sedimentary structures that trap and bind sediment constructed by communities of mat-building microörganisms. Their occurrence at 3 Ga is pretty strong evidence for the origins of life by that time. They exist today in the Bahamas and in Western Australia. Reading:  EE chapter 7 (Golubic).

 March 27 Life during Ediacaran time.

The organisms that lived during the end of Precambrian time were very different from those that rose to dominance during the Phanerozoic. This lecture surveys the creatures found during the Ediacaran Period as we attempt to comprehend their functional biology.


Section IV:  Earth Systems History

April 1 The evolution of biological complexity

The origin of complex multicellularity leads us to Haeckel’s gastrea theory vs. the synzoöspore and causes an examination of the position of complex multicellularity within the eukaryotic supertree.

April 3 The Cambrian Explosion

The sudden appearance of animals at 542 Ma remains one of the great unsolved puzzles of evolutionary biology.


April 8 Phanerozoic diversity.

The origin and early evolution of the Metazoa with emphasis on the fossil record. We take a brief look at the pattern of increasing diversity of life on Earth over the last 542 Myr. This pattern is greatly affected by environmental and climatic changes over millions of years in combination with evolutionary responses by species to local biological and environmental factors.

April 10 Grand cycles and the evolution of the oceans.

Until just a few years ago, the history of the composition of the oceans was considered to be essentially unchanged through geologic time. A new paradigm of alternating aragonite and calcite seas has now taken hold.


April 15 Terrestrial Ecosystems.

We look at the origin and evolution of plant life on land and the effects this has had on the changing Earth.


April 22 • QUIZ 4

April 22 Evolution of the atmosphere and climate

Changes in O2 and CO2 throughout Earth history have had (and are having) profound effects on all life on Earth. We review the geological evidence that documents these changes over time and discuss the impact they have had on the origin and evolution of life on Earth.



Section V:  Exobiology

April 24 The Gaia Hypothesis

James Lovelock and Lynn Margulis formulated the Gaia Hypothesis to help emphasize the importance of biological processes that influence the composition of the reactive gasses in Earth's atmosphere. The Gaia Hypothesis is often misunderstood to be more of a social phenomenon, but we will use it as a means to study the interaction between life and the Earth's life-sustaining environment. Reading: EE chapter 1 (Lovelock).


April 29 Of the Plurality of Worlds:  S.E.T.I. and the exoplanets

The Greenbank Equation is a generalized calculation about the probability of life elsewhere in the Universe. The search for extraterrestrial intelligence has received a boost in recent years with the continuing discovery of (exo)planets outside our own solar system.

May 1 The search for life on Mars

The early Viking experiments and ALH84001. Evidence of water and sedimentary rocks on Mars today. Course review.


May 12 @ 09:00 – 11:00   FINAL EXAMINATION   room 300 Higgins.


Course Particulars


Contact Information.--

Lecturer:  Paul Strother

Teaching Assistants:      Shaina Cohen “cohensv@mail.

Fernando Alverado “”

Email:, please use "GE146" in the subject header.

Office telephone: 617 552-8395 (MWF) or 617 552-1967 (TTh)

Office Hours: 1-2 pm Tuesdays and Thursdays, or by appointment.



Environmental Evolution (2nd ed.) by Margulis et al. (eds.). MIT Press. EE.

On the Origin of Species by Charles Darwin.

Any additional reading assignments will be announced in class.


1.     There will be 4 in-class lecture quizzes, each of which is worth 10% of your grade (40% total)

2.     Final Examination (35%)

3.     Lab grade (25%)

Examination policy.—You may use your class notes during quizzes and exams; however, they must be written by you and they must be in hardcopy.











update: January 14, 2014