EVOLUTION WITHOUT DIVERGENCE AND MULTIPLE ANCESTORS OF LIFE
Tatsuhiko Yagi1 and NobuoTamiya2
1
Shizuoka University, 836 Oya, Suruga-ku, Shizuoka 422-8529, Japan
2
Tohoku University, 6-3 Aoba, Aramaki, Aoba-ku, Sendai 980-8578, Japan
1asarlun@kitty.jp 2ntam@jg7.so-net.ne.jp(Received July 28, 2009; Accepted November 20, 2009)
sometimes they are inconsistent with that based onmorphology. This led us to propose a hypothesis thatthe main driving force for evolution is informationexchange (or communication) between different species,
rather than divergence of species resulting fromaccumulation of point mutations [4]. The horizontal
gene transfer may result in the morphology, behavior
and/or biochemistry of the living creatures. In thepresent paper some cases in which the mostfundamental metabolism is affected probably due togene transfer between the creatures of different groups
will be presented. In this hypothesis, which isschematically represented in Fig. 1, we postulated that
all the living things evolved not from a single ancestor,
but from multiple ancestors, and that an extensive
information exchange among species during evolution
makes much of, but not all of essential features of living
things in common. Actually, many of fundamental
features of living things are by no means in common,
which our hypothesis [4, 5] will cope with, but thesingle ancestor theory [1] will not. Moreover, evidence
for interspecies gene transfer is plenty [6-8]. In thispaper, we reinforce our hypothesis of “evolution
without divergence, or in other words, evolution byinterspecies communication,” and discuss possibility of
having multiple ancestors.

(Abstract)
Discrepancies among phylogenetic trees based on
different biopolymers and morphology, as well as
diversity of fundamental features in spite of generalbelief that most fundamental features are common to all
forms of life, led us to propose a hypothesis that the
major driving force for evolution is informationexchanges among different species, rather thandivergence of species resulting from accumulation ofpoint mutations. Mutations are mainly responsible forthe changes in the biopolymer sequences in different
species. Examples of diversity in biochemical featuresof living things dealt with include such fundamental
features as chirality of the membrane lipids,
mechanisms to mature mRNAs, synthesis ofaminoacyl-tRNAs, synthesis of isoprenoid precursors,coenzymes, etc. Admitting interspecies informationexchanges as the driving force for evolution, the life is
not necessarily originated from a single ancestor, but
the possibilities of multiple ancestors have to beconsidered. Several hypotheses for the origin of life,
which are consistent with multiple ancestors arepresented.
(Keywords)
evolution without divergence, multiple ancestors of life,
interspecies communication, horizontal gene transfer,chirality of membrane lipids, trans-splicing,aminoacyl-tRNA synthetases, phylogenetic trees,
phosphonate, CXXC sequence

2. Variety of Fundamental Features of Living
Things
The fact that most living things have essentially
identical pathways for the synthesis of such important
molecules as purine and pyrimidine nucleotides is
considered to be one of proofs for the single-ancestor
theory. However, detailed examination of biochemical
features demonstrates that the case of the nucleotide
synthesis is rather exceptional, and that many crucial
features and processes are by no means in common inliving things as shown below.

1. Introduction
It is commonly accepted as an established theory
that all the living things evolved from a single ancestor,
which emerged only once on our planet. The “facts”
supporting this theory summarized by Margaret
Dayhoff [1] are: (i) all the living things utilize ATP as
an energy mediator, (ii) synthesize and breakdown fats,carbohydrates and proteins by similar reactions, (iii)
live on proteins made of the same 20 amino acids, (iv)synthesize proteins by the same code system, and (v)utilize the same vitamins and other compounds. This
theory naturally leads to a conclusion that two
homologous proteins in different species (i.e.,
orthologous proteins) must have been diverged fromtheir common ancestral protein. This is the basis toconstruct the phylogenetic tree of living creatures foundin leading textbooks in biology and biochemistry [2, 3].
If this “single ancestor theory for the origin of life”
is actually the case, all the phylogenetic trees based on
any of orthologous protein families must be identical, or
must not have any discrepancy even if some trees lackbranches due to incomplete survey of orthologous
protein families. However, phylogenetic trees based on
different protein families are not always identical, andViva origino 37 (2009) 73 - 82
© 2009 by SSOEL Japan

2.1. Chirality of the membrane lipids
Cell membrane is one of the most important
constituentsofcellular
life,
of
which
glycerophospholipids constitute the main components.
The glycerophospholipids in bacterial and eucaryal cell
membranes are mainly long-chain carboxylate esters of
sn-glycero-3-phosphate(L-glycero-3-phosphate),
whereas glycerophospholipids in archaeal cell
membranesareisoprenoid
ethersofsn-glycero-1-phosphate (D-glycero-3-phosphate) as
shown in Fig. 2 [9-11]. It was postulated that Archaea
and Bacteria were diverged from a common ancestor
before cellular life [11], i.e., surface metabolist withoutcell [12], since the changeover from one enantiomer tothe other of glycerophosphate core in the membrane
phospholipids must have been impossible after once

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Viva origino 37 (2009) 73 - 82

Figure 1 Diagrammatic representation of our hypothesis, “evolution without
divergence.” Instead of postulating a single ancestor, this hypothesis assumes
possibility of having multiple ancestors (the number of ancestors is not necessarily
four as shown). Arrows indicate mutual information exchanges including horizontal
gene transfer by viral or bacterial infection, sex, hybridization (two-headed arrows), or
symbiosis (dotted arrows). This hypothesis does not deny divergence caused bymutations, but considers that mutual information exchange had major contribution to
the evolution.

Figure 2. Core compounds of membrane phospholipids in Bacteria and Eucarya (left), and Archaea (right). Only two
examples of hydrophobic tails are shown for each group of phospholipids. In membrane lipids, hydrophilic heads
such as glycerol, ethanolamine, L-serine, etc are esterified to the phosphate group of phosphatidate (in Bacteria andEucarya) or archaetidate/hydroxyarchaetidate (in Archaea).

2.2. Maturation of mRNAs
mRNAs play one of the most important roles in“the central dogma of molecular biology.” Procaryotic
mRNAs are polycistronic and matured without splicing,whereas eucaryotic mRNAs are monocistronic andmatured only after capping, polyA-tailing, and splicing.
Strategy of splicing in most Eucarya is that exons
upstream and downstream of each intron are connectedby transesterification to release the intron as a lariat, aprocess called cis-splicing, because two exons to becellular life was established. Rational to suggest thesurface metabolists as a common ancestor is the “facts”
that most basic biochemical features were shared byArchaea and Bacteria [13]. However, there are a lot ofdifferences in most fundamental features in these
Domains, as have been pointed out by Woese et al [14],and as will be described in this paper. Moreover, thesurface-metabolist hypothesis [12] does not rule out thepossible existence of more than two ancestors to evolveto Archaea and Bacteria (vide post).

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Viva origino 37 (2009) 73 - 82
Likewise, in some Archaea and Bacteria, Gln-tRNAGln
is not synthesized by Gln-tRNAGln synthetase (EC6.1.1.18), but is synthesized by the following successive
reactions [24]:L-glutamate + tRNAGln + ATP → Glu-tRNAGln +AMP + PPiEC 6.1.1.24
Glu-tRNAGln + L-glutamine + ATP → Gln-tRNAGln+ L-glutamate + ADP + Pi
EC 6.3.5.7
In this non-canonical aminoacylation of tRNAs,“mischarged” aminoacyl residues are prevented fromincorporation to protein, a phenomenon reminiscent of
the case for L-selenocysteinyl-tRNASec synthesis [25].
Some Archaea lack Cys-tRNACys synthetase (EC6.1.1.16), and Cys-tRNACys is synthesized bymoonlighting of Pro-tRNAPro synthetase [26], or from
O-phospho-Ser-tRNACys [27, 28]. Lys-tRNALys
synthetase (EC 6.1.1.6) belongs to class II AARS in
most Bacteria and a few Archaea, but belongs to class I
AARS in most Archaea and a few Bacteria [29].
Distribution of these non-canonical routes to synthesize
aminoacyl-tRNAs, marked on the phylogenetic tree
based on 16S rRNA [30, 31] is shown in Fig. 4.
L-Selenocysteine is regarded as the 21st aminoacid to be directly incorporated into protein byribosomaltranslation
machinery.
Likewise,
L-asparagine, L-glutamine, and L-cysteine areconsidered to be the latest members of the 20
established standard amino acids, and their respective
AARSs must have been the newest members in the
canonical AARS society. Then how did they widen
their distribution in living things? Interspecies
gene-transfer hypothesis will have no trouble to accountfor this rather irregular distribution.

connected are located on a single pre-mRNA molecule.
However, some eucaryal species including
Trypanosoma use a different strategy called
trans-splicing, in which a capped untranslatable exon
called a spliced leader (SL) and an exon containing an
ORF are derived from different pre-mRNA molecules.
Distribution of the SL-trans-splicing is shown in Fig. 3[15]. Pre-mRNAs of some species (e.g., C. elegans) aretranscribed as polycistronic units like those of
procaryotic operons, and are processed by
SL-trans-splicing to produce capped monocistronicmRNAs [16]. Different types of trans-splicing were
found in various species including Drosophila [17-19],
rat [20, 21], and even human [22], physiologicalsignificance thereof was assigned to produce diversity
in its essential proteins at least in case of Drosophila[17-19].
How can we explain the sporadic distribution oftrans-splicing based on the single ancestor theory? Is
this mechanism invented many times independently, oris it invented in the common ancestor and abandoned
randomly in very many unrelated species during
evolution? Instead, sporadic distribution oftrans-splicing mechanism must have been a result of theinterspecies information exchange.
2.3. Synthesis of aminoacyl-tRNAs.
Amino-acyl-tRNAs are indispensable materials
for the ribosomal protein synthesis encoded by mRNAs.
Until early 1990s, it was widely believed that all 20
standard amino acids were connected to their respective
tRNAs by ATP-driven two-step reactions catalyzed bytheir respective aminoacyl-tRNA synthetases (AARSs,
EC 6.1.1.class), and that the processes are common to
all living things. In late 1990s, some archaeal andbacterial Asn-tRNAAsn was found not to be synthesized
by Asn-tRNAAsn synthetase (EC 6.1.1.22) because of
absence of asparagine synthetase, but is synthesized by
the following successive reactions [23, 24]:
L-aspartate + tRNAAsn + ATP → Asp-tRNAAsn +AMP + PPiEC 6.1.1.23
Asp-tRNAAsn + L-glutamine + ATP → Asn-tRNAAsn+ L-glutamate + ADP + Pi
EC 6.3.5.6

2.4. Synthesis of isoprenoid precursors
Isoprenoid coenzyme Q is a key electron carrier inthe electron-transferring chain to create proton gradientacross biomembranes in many living things. Twoisoprenoid precursors, isopentenyl diphosphate anddimethylallyl diphosphate, are synthesized by themevalonate pathway in Archaea and Eucarya, and by
MEP pathway in most (but not all) bacterial species, inwhich 2-C-methyl-D-erythritol 4-phosphate (MEP) is a

Figure 3. Distribution of SL-trans-splicing species marked on a conventional phylogenetic tree, the branch lengths being arbitrary.

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Viva origino 37 (2009) 73 - 82

Figure 4. Distribution of canonical and non-canonical pathways to synthesize several amino-acyl-tRNAs, marked on the archaealand bacterial branches of the phylogenetic tree based on rRNA sequences [30, 31], the branch lengths being arbitrary. Upper-caseletters for canonical pathways, and lower-case letters for non-canonical pathways. C and c: Cys-tRNACys synthesis, K and k,
Lys-tRNALys synthetase (class II being regarded as canonical), N and n, Asn-tRNAAsn synthesis, Q and q, Gln-tRNAGln synthesis.

the route via Glu-tRNAGlu in plants and bacteria [34],and a detour to produce coproporphyrinogen III fromuroporphyrinogen III, in which two methyl groups(positions
1
and
7)
are
supplied by
S-adenosyl-L-methionine [35]. Some bacterial species
have polyphosphate-dependent glucokinase [36], andsome archaeal species have ADP-dependent kinases in
the glycolytic pathway [37, 38]. Some archaeal species
use coenzymes different from those used by mostBacteria and Eucarya. For example, tetrahydromethanopterin substitutes for tetrahydrofolate as a C1
carrier [39]. 5-Deaza-8-hydroxy-7,8-didemethylriboflavin, a redox constituent in archaeal coenzyme
F420, functions as a cofactor in DNA photolyase (EC4.1.99.3) of Bacteria Anacystis nidulans [40], but not in
E. coli. Coenzyme M (2-mercaptoethanesulfonate) had
been considered to be unique in archaeal methanogens,but was found to be contained in substrates for
2-hydroxypropyl-CoM lyase (EC 4.4.1.23), which is
involved in alkene metabolism of some Bacteria [41,42]. It is amazing why these examples of metabolic

key intermediate as shown in Fig. 5 [32]. The enzyme
isopentenyl-diphosphate isomerase (EC 5.3.3.2) isessential in the mevalonate pathway to convert
isopentenyl-diphosphate to dimethylallyl diphosphate,but the enzyme is auxiliary in the MEP pathway,
because it only fine-tunes the ratio ofisopentenyl-diphosphate and dimethylallyl diphosphate(Fig. 5). There are two kinds of the isomerase, type 1
and type 2. Type 2 enzyme differs from type 1 enzyme
in sequence, and in requirement of FMN and NADPH
cofactors [33].
Distribution of the mevalonate and MEP pathways,
as well as two types of isopentenyl-diphosphate
isomerases, marked on the phylogenetic tree based on
16S rRNA [30, 31] is shown in Fig.6.
2.5. Additional examples
Variety in fundamental features is not restricted tothose described above. There are 3 routes to synthesize
heme: two routes to produce 5-aminolevulinate, i.e., thewell-known route from glycine and succinyl-CoA, and- 76 -

Viva origino 37 (2009) 73 - 82

Figure 5. Pathways to synthesize isoprenoid precursors, isopentenyl diphosphate and dimethylallyl diphosphate.

such as we have seen in metabolic maps, signaltransduction system, etc, and (iv) difficulty of holding
the components of the system together until a cell
membrane is formed.
The hypothesis that horizontal gene transfer was
the major driving force of evolution, which was first
proposed in 1985 [4] and reinforced later [5], explains
diversity and sporadic distributions of essential
molecules and processes (Actually processes are
determined by enzymes and cofactor molecules, thesewill be referred to as molecules, hereafter). Instead of
totally uncontrollable mutations, interspecies genetransfer would bring about a wide spectrum of changes
in phenotype from as small as a change in a single
molecule to alteration of a total metabolic pathway togenerate new species, depending on the extent of genetransfer. Interspecies information exchange at very earlystages of evolution, or repeated or wide range exchange
would make the resulting molecules distributed widely

diversity have been neglected when the origin of life isdiscussed.
3. Multiple Ancestors of Life Forms
The idea of the single ancestor as the origin of life
may date back to 1933, far before Dayhoff’s description[1], when Frederick Hopkins made a comment on theadvent of life as “the most improbable and the mostsignificant event in the history of the Universe” (cited in
Ref 43). His comment sounds like that the naissance oflife is a miracle, and had never happened again on ourplanet. Dixon and Webb [43] explained the backgroundof his comment as (i) extraordinary biochemicalsimilarity expressed by all living matter (which we
presented examples against), (ii) difficulty in building
up complex proteins from amino acid mixture
assuming the conditions exist to condense amino acidmixture to catalytic polymers, (iii) improbability offorming protein mixture to form a continuous chain- 77 -

Viva origino 37 (2009) 73 - 82

Figure 6. Distribution of the mevalonate pathway and MEP pathway, as well as of two types (type 1, type2, or absent) of isopentenyl-diphosphate isomerases, marked on the phylogenetic tree based on 16S rRNA
[30, 31], the branch lengths being arbitrary.

In the following discussion, proteinoid refers toabiotically produced random polymer of amino acids,
whereas protein refers to polypeptide produced byribosomal translation. It has been argued that if
conditions were met to randomly polymerize
abiotically produced amino acids, any proteinoids
having specific function would have been produced invanishingly small amount, only to be destroyed by
non-specific hydrolytic activities of the co-produced
proteinoids, because the condensation products musthave been enormously heterogeneous, and mostproteinoids had rather hydrolytic activities [47-50]. It is
well known, however, that a peptide assumes stableconformation to resist proteolytic degradation if it binds
a specific small molecule as a cofactor or a ligand. Twocases of conformational stabilization will be considered
here.
Peptides with Cys-X1-X2-Cys sequences: Heme
is one of small molecules produced abiotically at thetime of chemical evolution [51], and thought to beincorporated in polypeptides either non-covalently or
covalently. In covalent hemoprotein such as
cytochrome c, two mercapto groups of Cys-X1-X2-Cys(CXXC) sequence bind heme by thioether bonds.
CXXC sequences also function as binding sites toiron-sulfur cluster in ferredoxins, to Fe(II/III) ion inrubredoxins, and become a redox-active site to makedisulfide in thioredoxins. In these redox proteins, thedistances between the two sulfur atoms are different indifferent types of redox proteins as shown in Fig. 7. It
was assumed that the distance of the two sulfur atoms
of a CXXC sequence in relatively stable local
conformation would have selected the cofactor or
ligand to bind during the era of chemical evolution. To
substantiate this hypothesis, semi-empirical molecularorbital program, MOPAC, was run for CXXC
tetrapeptides to see whether the S-S distances inenergetically optimized conformers fall in the distancesamong living matters, whereas information exchange atlater stages, or among limited species would make theresulting molecules distributed sporadically. In thisregards, the synthetic routes of nucleotides must havespread at very early stages of the origin of life, whereas
the synthetic routes of aminoacyl-tRNAs spread after
Archaea and Bacteria had been established, but before
the appearance of Eucarya. This conclusion does notconflict with the possible time schedule thataminoacyl-tRNAs must have appeared after the sourcesof nucleotides were made available.
The ways living things exchange genes are open
vertically and horizontally in various directions, namely
through sex, hybridization, symbiosis and infection.
Gene exchange through sex is efficient even among
human beings. Only in 33 generations, namely in 1000
years, theoretical number of ancestors exceeds 8×109,
which is larger than the world population. Symbiosis
and infection might have contributed gene transfer,
because the gene exchange between hosts andsymbionts could have happened (and will happen)
among remotely related organisms. Amoeba, infectedwith an endosymbiont became to require it as acytoplasmic component [44]. The Margulis’ proposal[45, 46] that eucaryotic organelles originated fromsymbiont Bacteria, is now widely accepted. Mutations
have mainly been responsible for the change in the
biopolymer sequences in different species.
Given the interspecies communication as main
driving force for evolution, the life is not necessarily
originated from a single ancestor, but the possibilities ofmultiple ancestors have to be considered, provided that
Dixon-Webb’s problems are to be solved. Somepossibilities to solve these problems (ii and iii, videsupra) will be presented.
3.1. Hypothesis of conformational stabilization ofproteinoids by ligand binding- 78 -

Viva origino 37 (2009) 73 - 82

Figure 7. Distances between the two sulfur atoms in Cys-X1-X2-Cys sequences in redox proteins. The S-S distances in the redox
proteins, updated from Ref 52, were calculated from the atomic coordinates deposited in the Protein Data Bank.

billion years, i.e., 9.5×1015 s), and 2.5% of 31Si
produced (N*) was recovered in organic
31
P-compounds after β-decay, followed by recoiling in
the organic soup [56]. One might wonder why organic
phosphates, instead of phosphonates, play pivotal roles
in current life. This is because phosphates arepotentially reactive but are kinetically stable, and areable to exist as monoesters, diesters, diphosphates,
triphosphates, etc, and that they can be transformed toother molecules without modification of organic moiety.
On the other hand, organic phosphonates cannot
substitute organic phosphate esters because of theirintrinsic stability, i.e., phosphonates played a role asscaffolds for the phosphate-dependent life form toappear. Are the modern phosphonates the metabolic
fossil, or new comers after the phosphate-dependent life
form was established? Sporadic distribution of ability tosynthesize organic phosphonates [57, 58] shown in Fig.
8, as well as the fact that the enzyme to make a C-P
bond (phosphoenolpyruvate mutase, EC 5.4.2.9) musthave appeared after the establishment of glycolytic
pathway to supply phosphoenolpyruvate, would
suggest that C-P bond producing activity may havebeen invented after the phosphate-dependent life form
had been established, and widen distribution by genetransfer.
Finally, two hypotheses which do not conflict withthe multiple-ancestor-hypothesis for the origin of life,
but not necessary the most prevailing, will be briefly
presented. One is GADV-protein world hypothesis, or
simply GADV hypothesis developed by Ikehara et al[59, 60], and the other, the surface metabolist theory of
Wächtershäuser [12].

shown in Fig. 7 [52]. For modern proteins, folding
begins with hydrophobic collapse to make a corefollowed by formation of secondary and tertiary
structure to achieve native structure [53]. Prebiotic
proteinoids with CXXC sequences would have boundto their respective cofactors or ligands to form cores
followed by formation of secondary and tertiary
structure, so as to survive proteolytic attacks byco-produced proteinoids to eventually becomeancestors of cytochromes c, ferredoxins, rubredoxins,
etc.
Phosphonates vs phosphate esters: The mostimportant biomolecules are phosphate esters andproteins having affinity thereto. Organic phosphateesters are stable in a time scale of laboratory
experiments, but are unstable to be completelyhydrolyzed in a much longer time scale during thechemical evolution, and would not have been able tobecome cores for polypeptide folding. However,organic phosphonates which have stable C-P bonds
could have become cores for polypeptide folding, toprotect that proteinoids from hydrolytic attack by
co-produced
proteinoids.
Proteinoids
without
phosphonate ligands would have been destroyed tosupply amino acid materials for further synthesis ofphosphonate-binding proteinoids. This would haveresulted in accumulation of phosphonate-liganding
proteinoids. The proteinoids with phosphonate ligands
would have had affinity to structurally similar
phosphate esters, and would have potential to become
enzymes to act on or to produce that phosphate esters.
Several proteinoids thus produced would have formedat least parts of a metabolic pathway which involves
that phosphate esters. Abiotic production of organic
phosphinates (which can be oxidized to phosphonates
without C-P bond breakage) was demonstrated byrecoil process of (n, γ)reaction of 31P to produce
radioisotope 32P [54]. Similar recoil reactions wereconfirmed with (n, γ)reaction of 30Si in organic soup to
produce 31Si which emits β-ray (half life: 156 min) to
become stable 31P atoms in organic compounds [55].
The amount of organic phosphorus including
phosphates, phosphonates, and the reduced derivatives
thereof must have been 3×107 mol during chemical
evolution, calculated by the following equation: N* =Nσφt, where N* is the amount of 31Si produced, N, theamount of 30Si in the 1 m-depth surface of the earth(3.3×1017 mol), σ, the reaction cross section for thermal
neutrons (4×10-29 m2), φ, the neutron flux 35 billion
years ago (1×104 m-2 s-1, minimum estimate), and t, theduration of chemical evolution (assumed to be 0.3

3.2. GADV hypothesis
This hypothesis denies the RNA-world, and insiststhat the life originated from GADV-proteins,proteinoids with random sequences of only 4 aminoacids, glycine (G), alanine (A), aspartate (D), and valine(V). This hypothesis is based in part on the catalytic
activities observed for heat-polymerized GADV
mixture [59]. Rather simple constituents would
minimize the heterogeneity of the polymerized
products, and increase the probability of the appearanceof “meaningful” proteinoids, which would have paved
a way to appear multiple ancestors of life. Although thishypothesis does not suggest the mechanism forgrowing number of standard amino acids from 4 to 20,
if combined with Akabori’s polyglycine hypothesis[61], glycyl residues in the GADV-proteinoids havepotential to be modified to seryl residues, which in turn

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Viva origino 37 (2009) 73 - 82

Figure 8. Distribution of the ability to produce C-P bonds, marked on a conventional phylogenetic tree, the branch lengths being
arbitrary. C-P compounds include ciliatine (2-aminoethylphosphonate), N-methyl derivatives thereof, 3-phosphonoalanine, etc in
free, or as components in phosphonolipids.

the concentration of the building block molecules musthave been to low, and polymerization would have been
impossible in a thermodynamic viewpoint. The surface
metabolist theory aims at evading this thermodynamic
constraint. Linking two molecules to a bigger moleculein surface reaction, loss of the degrees of freedom (ΔS)
must be much less compared to three-dimensional
solution reaction to make the condensation reaction
more feasible. This theory dictates a course of evolution
from the surface metabolists to life through cell
formation, evolution of genetic machinery, etc.
Although this hypothesis was severely criticized by de
Duve and Stanley Miller [62], it is worthy to give aglance at this aggressive, revolutionary, and fascinating
theory, which does not conflict with the naissance ofmultiple ancestors.
We presented three possible hypotheses for themultiple ancestors of life forms, the hypothesis ofare eligible to become tyrosyl, histidyl, tryptophanyl
residues, etc, by condensation with phenol, imidazole,
indole, etc, to result in a complete set of contemporary
standard amino acids.
3.3. Surface metabolist theory
In this hypothesis [12], the surface metabolists aredescribed as “These organisms are acellular and lack amechanism for division, yet they can grow. They
possess neither enzymes nor a mechanism fortranslation, but they do have autocatalytic metabolism.
They do not have nucleic acids or any other template,
yet they have inheritance and selections. Although they
can barely be called living, they have a capacity forevolution.” In most hypotheses of the origin of life,
polymerization of amino acids and other building
blocks in primordial soup was postulated to be driven
by local concentration and heating of the soup, or else,- 80 -

Viva origino 37 (2009) 73 - 82
conformational stabilization of proteinoids, the GADV
hypothesis, and the surface metabolist theory. Some ofthese hypotheses are mutually incompatible, but if we
admit appearance of multiple ancestors followed bywidespread interspecies communication, multiple ways
for the naissance of life may be acceptable.
4. Conclusion
Evidence is presented to suggest that life
originated from multiple ancestors, and the major
driving force of evolution has been (and will be)interspecies communication. Mutations have mainly
been responsible for the changes in sequences of
biopolymers in different species. Some hypotheses arepresented which are consistent with the multiple
ancestors of life forms.
Acknowledgements
We are indebted to Professor Noriko Fujii, Kyoto
University, for encouraging us to present our hypothesison the origin of life and evolution.
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