Mom, Florence Fogel, Marilyn (scowling like my brother) and Dad, Arthur Fogel, Graduation Penn State 1973 |
Barghoorn noted that life had to
conquer three different thresholds to evolve to where it is today. From the
chemical soup of the early Earth, organisms needed to develop biosynthetic
pathways such as photosynthesis. He presumed that the first organisms were
heterotrophs, feeding on compounds in the chemical soup. Barghoorn argued that
autotrophy—making biomass like plants do today-- was also needed to continue
the supply of organic nutrients for heterotrophs. The second threshold was
diversification, whereby single celled organisms needed to develop into more
complex forms, including chains of cells or stromatolites, macro structures
seen in sediments over the years.
The third threshold that organisms
needed to transcend was the formation of cellular microstructures, notably the
nucleus, in order to become multicellular organisms. Sedimentary deposits from
three different continents, Africa, Australia, and North America confirmed to
Barghoorn, Schopf and others that life was widespread on the earth during its
first 2 billion years and had originated in similar fashion across the planet.
The conclusion that these were fossil
microbes (Schopf and Barghoorn, 1967) started a four-decade debate about the
biogenicity of these structures found in ancient rocks. The authors noted that
although it is difficult, I would say impossible, to relate the potentially
biological structures to intact cells, they concluded that the spheroids are
“almost certainly of biological origin” representing cells, most likely algae.
Electron microscopy of ancient sediments was a new technique at the time.
Microscopic examination coupled with chemical and isotopic analyses seemed to
prove the interpretation that these were fossil organisms. Their paper
certainly caught my eye and my interests because it combined new chemical
instrumentation to describe once-living organisms in a geological context.
These three fields of science--biology, chemistry, and earth science--rolled
into one sparked my career.
At Penn State, two experiences largely
determined my interest in these fields: a 3-month Marine Science quarter at
Wallops Island, Virginia, and a special class in Geochemistry. Both of these
opportunities were sparked by my friend Nancy “Natasha” Peters. “Nat” and I met
first quarter in summer 1970 when we lived on the third floor of Curtin Hall.
We were both out of state students, thrust into the rural atmosphere of State
College—she from the DC area, me the Philadelphia suburbs. That summer we were
introduced to a group of renegade fraternity guys who inducted us into their
frat with a ceremony complete with robes, candles, and the secret handshake.
After that experience, we were partners in adventure for the next three years.
Nat was a biochemistry major, aced all her exams, but wasn’t bitten by the same
science bug that I was. She heard about the marine science program and wrangled
us, just technically juniors, into a competitive list of students chosen to
participate.
Nancy Zeller at Wallops Island, 1972 |
Wallops Island Station is a former Navy
base on the coast of southern Virginia. It also served then and now as an
outpost for NASA satellite tracking and small rocket launches. In March 1972, forty
Penn State students led by Professor Albert Guber from the Earth Science
Department moved into former Naval officer quarters on the outskirts of the
base. There were only 4 women in the group---Nat, Nancy Zeller, and me, all
long time friends, and one other. As students in the first class to start this
program, we were pioneers. The quarter was broken into three segments in which
we concentrated on subjects—Physical Oceanography, Marine Biology, and
Geological Oceanography. It was heaven on earth for me as a student. Our
studies consisted of evening lectures with day times spent in the field in the
neighboring environments of Chincoteague and Assateague Islands and beaches. Weekly
we went out on small boats in the bays and offshore collecting sediments, water
samples, and marine organisms that we kept alive in tanks in our lab.
Nancy Zeller, Nat, and I pitched in our
meager resources and with the help of Nancy’s dad purchased a small skiff with
an outboard motor that we moored under a bridge on the road to Chincoteague.
The inlet opened up to miles of pristine salt marsh with its green Spartina grasses, oyster beds, and tidal
flats beckoning us to investigate their mysteries first hand. When we had a
slow day, we got in that little boat in early morning, making temperature and
salinity measurements, digging up clams that we cooked for dinner, and just
plain immersing ourselves in the environment. Years later this experience
influenced my choice of research projects. I was now thoroughly hooked and
prepared to do whatever was necessary to make marine science a career.
Nancy Zeller, Marilyn and sister Barbara, Penn State 1973 |
We learned about petroleum and coal
formation, how living organisms decayed and entered the fossil record, and
about the origin of life on Earth. The research on Earth’s earliest life was
all very exciting for me. Given revealed a set of fascinating papers to our
small group of undergraduate and graduate students. I was immediately hooked!
As a biology major, I wanted to know how to identify chert, the rock type where
fossils were found. I wanted to use my fascination with biochemistry to find
molecular fossils. Last but not least, ironically at the time, I was not at all
interested in the carbon isotope papers published by Tom Hoering (1963; 1967)
and others. Little did I realize then that carbon isotopes and the process of
isotope patterning by blue-green algae (cyanobacteria) would come to occupy the
majority of my research career.
Prof. Given’s class was a huge eye
opener for me in many ways. I was able to use my knowledge and love of
chemistry to begin to understand biological, environmental, and ecological
processes. In the 1960s, scientists at the Carnegie Institution led by Philip
Abelson, Tom Hoering, and P. Edgar Hare were discovering simple molecules like
fatty acids in marine sediments and fossil shells (Abelson et al. 1956; Hare
and Abelson, 1968). Then postdoctoral fellow Patrick Parker published a
landmark paper (Parker, 1964) in which he not only described the molecular
distributions of fatty acids in marine organisms, but isolated these molecules
to measure their carbon isotope patterns. Parker and colleagues at the
University of Texas Marine Science Institute (UTMSI) were publishing papers at
a rate of one a year in the journal Science on new compounds found in
sediments, marine ecosystems, and blue-green algae.
At the conclusion of my undergraduate
years as a biology major, I was convinced that I wanted to combine biology,
chemistry, and geology in an interdisciplinary career. Professor Given helped
tremendously by suggesting two United States labs and one British group, that
were engaged in the research I was most interested in. I chose to attend the
University of Texas Marine Science Institute (UMTSI) in Port Aransas based on a
welcoming phone call from Professor Patrick L. Parker. Pat Parker provided a
positive response to my potential and offered me a position as a graduate
student in an interdisciplinary course of study under the joint supervision of
Parker (a marine organic geochemist), Chase Van Baalen (an algal physiologist
and specialist in cyanobacteria), and Bill Behrens (a marine geologist). I
accepted the position and in January 1974 I headed south to Port Aransas,
Texas, on the coast of the Gulf of Mexico. In hindsight, my decision to study
at UTMSI with Parker was without question, the right choice. Parker’s research
on the relationship of modern organisms to the compounds found in Recent
sediments, as well as his interest in carbon isotopes, set the path for my
career in biogeochemistry.
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