The Science of Bodybuilding

Adventures in Bodybuilding

• The graduate career involved staring into microscopes to observe how cells form bones.
• The developing limbs of salamanders or frogs were stained to turn developing cartilage blue and bones red, with glycerin used to clear the remaining tissues.
• Early embryos have tiny limb buds with evenly spaced cells inside.
• In older embryos, cells take different shapes, and the bones form, where each clump seen during early stages becomes a bone.
• Bodies are assembled like brick houses where limbs are constructed by smaller pieces.
• Houses rely on builders, knowing the placement of each brick, while limbs contain construction information in each cell.
• Animal bodies develop spontaneously, as if houses assembled from all the information in the bricks.
• Cell attachment, communication, and the materials created determine how bodies look different from each other, like the difference between a human and a jellyfish.
• Cell cooperation is essential for making a body, needing coordination to create new kinds of individuals.
• Not every cell clump becomes a body, distinguishing a mat of bacteria from an individual.
• The thought experiment shows when removing bacteria results in a smaller mat while removing animal cells leads to death, depending on the cells.
• Bodies involve component parts working together where a necessary division of labor exists between parts like the brain, heart, and stomach.
• A body or person has an identity its organs, tissues, and cells lack.
• Despite constant turnover, organs maintain their size and place in the body through cell communication, maintaining integrity and surface regularity.
• Disruption of balance among body parts leads to death.
• Cancer occurs when cells no longer cooperate, dividing endlessly or failing to die.
• Ancestors shifted from single-celled to bodied organisms a billion years ago.
• The shift required new mechanisms for cells to work together, communicate, stick together, and make new molecules.

Digging Up Bodies

• Most of Earth's history is the story of single-celled creatures.
• Animals with hands, heads, sense organs, and body plans have been around for a small fraction of history.
• Earth's entire 4.5-billion-year history can be scaled down to a single year.
• Until June, the only organisms were single-celled microbes, such as algae, bacteria, and amoebae.
• The first animal with a head appeared only in October, humans appeared on December 31.
• Rocks older than 600 million years lack animals or plants, and only contain single-celled creatures or algae colonies.
• Early fossils were found between 1920 and 1960 but were initially unrecognized.
• Martin Gurich discovered impressions of animal bodies in Namibia in the 1920s and 1930s.
• In 1947, Reginald Sprigg discovered impressions of disks, ribbons, and fronds in the Ediacara Hills of South Australia.
• Martin Glaessner, in the mid-1960s, showed these fossils were 15 to 20 million years older than previously thought.
• These are the earliest bodies, dating from the Precambrian period.
• Precambrian means "Before Life."
• Precambrian disks, ribbons, and fronds are the oldest creatures with bodies.
• Early fossil animals are sponges and jellyfish.
• Precambrian fossils have patterns and structures suggesting a level of new biological organization.
• The first trackways are seen in the rocks from this period showing evidence of creatures crawling and squirming through the ooze.
• First bodies appeared before body plans, showing how ordered the rocks of the world are.
• Precambrian discoveries reveal when bodies arose.
• The "stuff" making up our bodies is the same as that in fossils discovered by Gurich and Sprigg.
• Scaffolding for our bodies originates from single-celled animals.

Our Own Body of Evidence

• Biological glue in creatures holds cells together, allows cell communication, and forms structure.
• Glue is a variety of molecules located between cells.
• Tissues and organs have functions and appearances, differing in cell and material arrangement internally.
• The shape of cells and their attachment to one another are clues, along with the stuff that lies between them.
• Tissues have various cells attaching in different ways (strips, columns, scattered).
• Properties of tissues are often gained from the materials filling them.
• The arrangement of cells and intercellular materials allows students to identify organs from microscope slides.
• Molecules make cellular arrangements possible.
• No way to attach cells or materials between cells means just batches of cells.
• Focus in detail on the skeleton to understand the relevance of the molecular structure in our bodies.
• The skeleton exemplifies principles applying to the body's parts.
• Without skeletons, we would be formless.
• A skeleton provides structure and aids movement.
• Bone strength relies on proportions of building materials (girders and cables) and microscopic properties.
• The molecular structure of steel and the molecular properties of our bones determine their strength.
• Muscles contract, feet push, and bones/joints act as levers/pulleys.
• Body movement is based on physics: size, shape, skeleton proportions, and joint configuration.
• Bone design matches body function.
• Microscopic view: cells are organized/separated, and materials define the strength of bone.
• Strength is determined by materials between cells.
• Hydroxyapatite is strong when compressed.
• Bone shapes maximize compression and minimize bending: Bones = concrete or bricks.
• Collagen is the most common protein in the human body.
• Viewed with an electron microscope at 10,000x magnification collagen appears as a rope of bundled fibers.
• Collagen functions like a rope: strong when pulled, weak when compressed.
• Bones are composed of a sea of hydroxyapatite and collagen with strength based on the amounts of each molecule.
• During our jog, our bones glide against one another during cartilage in our joints, working differently.
• Cartilage is pliable, bending and smushing as forces are applied to it.
• The function of the knee joint relies on having soft cartilage.
• When cartilage is compressed, it returns to its former shape.
• Without cartilage, bones would grind against one another, leading to arthritis.
• Cartilage contains relatively few cells and a lot of interstitial filling that largely determine the mechanical properties of the cartilage.
• The major property of cartilage is the Collagen filling.
• Collagen with a proteoglycan complex gives cartilage strength when squeezed or compressed, like joint pads.
• The cartilage cells secrete and maintain molecules.
• Ratios of materials define mechanical differences for bone, cartilage, and teeth and the collagen/proteoglycans present.
• Bodies have molecules that lie between their cells (collagens/proteoglycans).
• Collagen makes up over 90% of body's protein.
• Bone cells stick together and communicate.
• Cells in bones attach and behave differently.
• Molecular rivets (diverse) bind bone cells together and form contact cement (firm attachment).
• Rivets are organized to allow cell organization (bone to bone, skin to skin).

Bodybuilding for Blobs

• Cells require knowledge of when to divide, make molecules, and die.
• Cells communicate with "words" (molecules) that move from cell to cell.
• A signal is sent by one cell and attached to the outer covering or membrane of the receiving cell.
• The molecular signal causes genes to be turned on/off.
• The cell receiving the signal now changes its behavior (dies, divides, or makes molecules).
• Animals with bodies have structural molecules such as collagens and proteoglycans, molecular rivets, and molecular tools.
• Understanding how bodies are made requires looking for these molecules in the most primitive bodies.
• A blob like professor in the movie The Blob, shares some things with living creatures today.
• A strangely simple creature was discovered living on the glass walls of an aquarium in the 1880s.
• Placozoans are organisms with around 200-1,000 cells, about 2mm in diameter
• Placozoans have four cell types and simple bodies shaped like a small plate which are specialized for digestion and have flagella used to move the creature.
• Primitive creatures have a division of labor among their parts, where bodies already exist.
• Much of our bodybuilding apparatus exists in placozoans.
• They have versions of cell communication tools and molecular rivets.
• The building apparatus is found in simpler blobs than Reginald Sprigg's ancient impressions.
• Sponges consist of a matrix (silica or calcium carbonate) with some collagen interspersed.
• Collagen is a major part of tissues holding cells together.
• H.V.P. Wilson showed sponges have amazing capabilities.
• Putting a sponge through a sieve broke it down to disaggregated cells which crawled around.
• The cells came together, formed red cloudy balls, gained patterns, and the clump formed a new sponge body.
• Sponges have many important properties of bodies: division of labor, cell communication, array of cells function as a single individual.
• Like placozoans and sponges, we have many cells and division of labor among parts.
• Placozoans and sponges all have collagen, but are simple.
• Animal and microbe genomic comparisons show many single-celled animals lack cell adhesion machinery.
• The tools to build bodies should arise in lockstep with bodies.
• Nicole King found that choanoflagellates are likely the closest microbe relatives of animals with bodies, placozoans, and sponges.
• King suspected that choanoflagellates DNA is the version that makes our bodies.
• Information from Human Genome Project led to genetic tools to study choanoflagellates.
• Choanoflagellates look like the goblet-shaped cells inside a sponge.
• People thought they were degenerate sponges.
• Microbe sponge DNA similarities are shown by the choanoflagellates DNA and they are single-celled microbes.
• Nicole's work broke down genetic distinction between "single-celled microbe" and "animal with body."
• Genes in choanoflagellates are also active in animals (machinery that builds bodies).
• Cell adhesion and cell communication are some of the few reasons for this comparison.
• Choanoflagellates show communication, cell adhesion, matrix, and molecular cascades.
• A road map for comparing our bodybuilding apparatus is known from Choanoflagellates research.
• Streptococcus bacteria have a molecule similar to collagen on their cell surface, however does not form ropes or sheets.
• Protoeoglycan complexes can be seen in bacterial cell walls.
• Microbes use molecules that cause humans misery are versions of what makes our own bodies possble.
• After 3.5 billion years microbes, bodies appeared within 40 million years.
• Bodies were a fad.

A Perfect Storm in the Origin of Bodies

• Potential to build bodies was in place before bodies ever hit the scene.
• One theory states bodies came to be when microbes developed new ways of being eaten or eating so bodies were a type of defense.
• The interplay between predators and prey may have led to bodybuilding molecules, where microbes attach and engulf.
• Martin Boraas showed how predation could create bodies.
• Algae was normally a single-cell and lived for over a thousand generations in a lab.
• A predator was introduced which was a single cell creature that engulfs microbes.
• The algae became clumps of hundreds of cells.
• Clumps had eight cells to avoid being eaten and get light.
• The predator was removed and algae continued to reproduce and form individuals with eight cells.
• A multicellular form came from something similar.
• Over time, bodies developed.
• The world may not have been ready for bodies and bodies are expensive to have.
• Having bodies means avoiding predators, eating other creatures, and actively moving long distances.
• Body advantages: control environment (energy needs).
• Large bodies (collagen incorporation) require even more energy needs.
• Collagen synthesis increases need for metabolic element.
• The problem was low levels of oxygen.
• Oxygen increased roughly a billion years ago.
• Rocks signature having been formed with increasing oxygen.
• Microbes developed interactions with environment and each other hitting molecular parts and tools.
• The reason was microbes built bodies by eating each other.
• Molecular tools were required to do so.
• Enough oxygen allowed for the world to support bodies.