What is life?

M Anbar

doi:10.1109/51.932719

Home/Archive/PubMed

PubMed · 11446204

What is life?

M Anbar

View original source ↗Export metadata ↓

Abstract

Life is a composite process in nature that is as fundamental as the laws of physics that govern the behavior of the inanimate world. The laws of physics change qualitatively as we go from the macroscopic to the atomic and subatomic domains. Likewise, the behavior of living systems changes dramatically when a certain level of complexity, including social organization, has been reached. Moreover, live systems may change the projected course of the inanimate world, as they are already doing on our tiny planet. In brief, life does not only "make the world turn around," it can do this for the whole universe. Consequently, life is probably the most significant process in nature; it is also the least predictable. The behavior of live systems is unpredictable. Unlike the inanimate universe that can be readily modeled using a limited number of parameters, the perpetually increasing complexity of living systems defies modeling. If we would have used all the information available about the behavior of live systems on this planet just five million years ago, we could never have come up with a model describing human civilization of today. Such a prediction would have been, obviously, much harder if we knew everything about living systems on this planet five hundred million years ago. The nonpredictability of the behavior of living systems is not solely due to its stochastic nature. The behavior of live systems is unpredictable because it is based on interactions among millions of independent or partially dependent stochastic processes involving both live and inanimate systems. The number of different pathways constituting such behavior is virtually infinite. This makes the predictability of such behavior qualitatively different from that of conventional stochastic behavior, which is based on a finite number of parameters, each with a finite number of degrees of freedom. Furthermore, unlike statistical mechanics, which are applicable to inanimate systems, the behavior of living systems cannot be delimited by an analog to Heisenberg's uncertainty principle. The answer to the question "What is life?" is, in brief: Life is a multifunctional process in nature that is as fundamental as the basic "laws" of physics, used to model the behavior of the inanimate world. Like those "laws," life can control the behavior of our universe, including its lifespan.

Explore related subjects

Biological Evolution Extraterrestrial Environment Humans Life Origin of Life Editorial

Keep this discovery

Explore connections, maps & timelines

BibTeX RIS

M Anbar. What is life?. https://doi.org/10.1109/51.932719

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related citations

PubMed2026

Rapid and repeated evolution of increased competitive ability in a global invader.

Rapid adaptive evolution can increase the competitive ability of invasive species in their non-native ranges. However, whether this increase is a general response and what drives it remain uncertain because the evidence is largely based on studies with limited sampling, inadequate consideration of population co-ancestry, and oversimplified estimates of competitive ability. We conduct a large-scale glasshouse experiment testing the effects of competition and drought on 100 native and 165 non-native populations of Erigeron canadensis, all genotyped to account for co-ancestry. Plants from non-native populations are significantly more competitive against other species than the conspecifics from native populations under both mesic and dry conditions. Genetic clustering indicates that the rapid evolution of competitive ability occurs independently in two out of four clusters in the non-native range. This advantage is present only during interspecific interactions and is absent during intraspecific competition. Repeated evolution of increased competitive ability suggests that adaptation following introduction can reshape species interactions and promote invasion success, even under future drought conditions, highlighting the importance of rapid evolution in determining the ecological impacts of invasive plants.

Biological Evolution↗

PubMed2025

Genomic signature and evolutionary history of completely cleistogamous lineages in the non-photosynthetic orchid Gastrodia.

Despite a long-standing interest since Darwin's time, the genomic implications of obligate self-fertilization remain elusive. Complete cleistogamy-the obligate production of closed, self-pollinating flowers-represents an extreme reproductive strategy. Here, we present the genomic profiles and evolutionary history of two lineages of the mycoheterotrophic orchid Gastrodia, both of which independently acquired complete cleistogamy, based on detailed sampling and a combination of simple sequence repeat (SSR), multiplexed ISSR genotyping by sequencing (MIG-seq) and RNA-seq data. Our analysis reveals clear species delimitation, with no evidence of introgression between the completely cleistogamous species and their co-occurring allogamous sisters. Intriguingly, all analyses indicate that both the completely cleistogamous Gastrodia species and their allogamous sisters exhibit genetic profiles typical of self-pollinating plants. This pattern suggests that their ancestors, probably bearing allogamous flowers, had already evolved mechanisms to mitigate the deleterious effects of selfing, potentially facilitating the emergence of complete cleistogamy through benefits such as reproductive assurance, enhanced colonization ability and species reinforcement. Meanwhile, further analyses suggest that complete cleistogamy evolved very recently (possibly within the last 1000-2000 years) in these two Gastrodia lineages. Combined with the scant evidence of complete cleistogamy outside Gastrodia, our findings imply a limited and ephemeral role for complete cleistogamy in plant speciation.

Biological Evolution↗

PubMed2022

The evolutionary dynamics of extrachromosomal DNA in human cancers.

Oncogene amplification on extrachromosomal DNA (ecDNA) is a common event, driving aggressive tumor growth, drug resistance and shorter survival. Currently, the impact of nonchromosomal oncogene inheritance-random identity by descent-is poorly understood. Also unclear is the impact of ecDNA on somatic variation and selection. Here integrating theoretical models of random segregation, unbiased image analysis, CRISPR-based ecDNA tagging with live-cell imaging and CRISPR-C, we demonstrate that random ecDNA inheritance results in extensive intratumoral ecDNA copy number heterogeneity and rapid adaptation to metabolic stress and targeted treatment. Observed ecDNAs benefit host cell survival or growth and can change within a single cell cycle. ecDNA inheritance can predict, a priori, some of the aggressive features of ecDNA-containing cancers. These properties are facilitated by the ability of ecDNA to rapidly adapt genomes in a way that is not possible through chromosomal oncogene amplification. These results show how the nonchromosomal random inheritance pattern of ecDNA contributes to poor outcomes for patients with cancer.

Biological Evolution↗