What Does It Means to Be 98% Chimpanzee? Book by Jonathan Marks


“In his book, What Does It Means to Be 98% Chimpanzee? Jonathan Marks explains comparisons based on the percentage of similarity (or difference) of DNA sequences are largely Meaningless. He points out the fact that humans and daffodils possess a 35 percent genetic similarity. According to Marks, In the context of a 35% similarity to a daffodil, the 99.44% of the DNA of humans to chimp doesn’t seem so remarkable. After all, humans are obviously a heck of a lot more similar to chimpanzees than to daffodils. More than that, to say that humans are over one-third daffodil is more ludicrous than profound. There are hardly any comparisons you can make to a daffodil in which humans are 35% similar.” -F Rana

While humans and chimpanzees share over 98% of their DNA, the way those genes are used, or their gene expression, plays a major role in the vast differences we see in both our biology and behavior. It's a fascinating shift in perspective from simply counting genes to understanding how those genes are turned on and off by epigenetics and how that shapes us.

Here are some key points to consider:

  1. Regulatory elements: Tiny stretches of DNA upstream or within genes act as switches, activating or silencing those genes. These regulatory elements differ significantly between humans and chimps, leading to variations in gene expression even for seemingly identical genes.

  2. Alternative splicing: This process allows a single gene to code for multiple proteins by splicing together different combinations of its exons (coding regions). Humans have a much higher rate of alternative splicing than chimps, leading to a greater diversity of proteins and functional consequences.

  3. Non-coding DNA: Once thought of as junk, non-coding DNA now plays a crucial role in gene regulation. Differences in these regions between humans and chimps can significantly impact gene expression patterns.

  4. Epigenetics: The chemical modifications on DNA and surrounding proteins influence gene expression without changing the DNA sequence itself. These epigenetic marks can differ significantly between individuals and species, contributing to variations in biology and behavior. For instance identical twins, same blueprint, different expressions. Epigenetics acts like a master conductor, orchestrating gene expression without changing the notes (DNA). Chemical switches like methyl groups silence or amplify genes, shaping diverse cell types and traits. One twin may be schizophrenic and the other have heart disease.

In a butterfly, these switches might dimmate wing color, while in a human, they could boost brain development. Environmental whispers, from early nutrition to stress, can tune these switches, creating unique phenotypes from shared genes. Think of it as dimming a room's lights instead of rewiring the whole circuit. This dynamic dance between genes and environment allows even identical twins to express their individuality, all thanks to the unseen conductor – epigenetics.

This calls for comparative epigenomics as identical genotypes can cause very different phenotypes.


Comparative genomics ignores these epigenetic changes.


Understanding these mechanisms helps us move beyond the simplistic "gene for X trait" mentality and appreciate the complex interplay between genes, their regulation, and environment in shaping human and chimp characteristics.

It's worth noting that while gene expression plays a vital role, differences in the types of genes present can also contribute to some biological and behavioral distinctions. For example, the presence of a specific gene in humans, not present in chimps, may be responsible for some unique human traits.

Overall, gene expression is of critical importance in understanding the differences between humans and chimps, causing us to move beyond a purely gene-counting approach and acknowledging the intricate dance between genes, their regulation, and the environment in shaping the diversity we see in the living world.

"98% the same?” Why we need an Extended Evolutionary Synthesis 

Jonathan Marks' provocative book, "What Does It Means to Be 98% Chimpanzee?", throws a grenade into the comfortable camp of the modern synthesis, the dominant theory explaining the evolution of life. This theory posits that natural selection acting on genes is the primary driver of evolutionary change.

Marks challenges this notion by arguing that the modern synthesis neglects the crucial role of culture in shaping human evolution. He highlights the vast gulf between us and our closest primate relatives, chimpanzees, despite sharing 98.8% of our DNA.

The Rise of Culture

Marks asserts that culture, encompassing language, social norms, technology, and artistic expressions, acts as a potent evolutionary force in its own right. He argues that cultural innovations can be transmitted and accumulated much faster than genetic changes, leading to rapid and profound shifts in human behavior and society.

For example, the development of agriculture dramatically altered our diet, social structures, and even physical characteristics. Similarly, the invention of language revolutionized our ability to communicate and collaborate, paving the way for complex social organization and technological advancements.

Calling for the Extended Evolutionary Synthesis

In light of culture's undeniable impact, the concepts in Mark's book calls for an extension of the modern synthesis, incorporating cultural evolution alongside genetic evolution. This extended evolutionary synthesis recognizes that natural selection operates not just on genes but also on cultural traits, leading to a more complete understanding of human evolution.

Implications of the Extended Synthesis

The extended evolutionary synthesis has far-reaching implications. It challenges notions of genetic determinism, suggesting that our behavior and capabilities are not solely dictated by our genes but also shaped by the cultural environment we inhabit. It also underscores the importance of cultural diversity and understanding the unique evolutionary trajectories of different societies. 

Concepts outside of the Modern Synthesis include:

Epigenetics; Constructive development and reciprocal causation; Multilevel selection; Niche construction; Evolvability; Transgenerational epigenetic inheritance; Developmental bias; Inclusive inheritance; and Emphasis on phenotypic variation and organism-environment interactions.

Moving Beyond the 98%

Ultimately, "What Does It Means to Be 98% Chimpanzee?" is not about obsessing over a specific percentage. It's about urging us to move beyond simplistic narratives and embrace the intricate tapestry of human evolution. By acknowledging the interplay of genes and culture, we can gain a deeper appreciation for the remarkable journey that led to the emergence of our unique species.

In conclusion, Marks' book is a compelling call for a more comprehensive understanding of human evolution, one that recognizes the profound influence of culture and paves the way for a more inclusive and nuanced appreciation of human diversity.

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